Updated March 13: ABC News and CNN have reported that the soldier who allegedly killed 16 Afghan civilians previously suffered a traumatic brain injury during one of his four deployments, citing unnamed Defense Department sources. As part of our extensive coverage of traumatic brain injury, ProPublica featured a unit of soldiers dubbed "Psycho Platoon" who sustained brain injuries in Iraq and had severe mental health challenges when they returned from their deployments. In another story, we also visited Fort Lewis, where the soldier accused of the killings was based. While there, we talked to soldiers about how they are assessed for brain injuries.

A version of this story was co-produced with NPR and aired on All Things Considered. (Listen here.) This story was also published as part of Amazon's Kindle Singles program, and is available for reading on that device.

MINOT, ND -- At 8:20 p.m. on Sept. 21, 2010, Iraq veteran Brock Savelkoul decided it was time to die. He lurched from his black Tacoma pickup truck, gripping a 9-mm pistol. In front of him, a half dozen law enforcement officers crouched behind patrol cars with their weapons drawn. They had surrounded him on a muddy red road after an hour-long chase that reached speeds of 105 miles per hour. Savelkoul stared at the ring of men and women before ducking into the cab of his truck. He cranked up the radio. A country song about whiskey and cigarettes wafted out across an endless sprawl of North Dakota farmland, stubbled from the recent harvest. Sleet was falling, chilling the air. Savelkoul, 29, walked slowly toward the officers. He gestured wildly with his gun. "Go ahead, shoot me! ... Please, shoot me," he yelled, his face illuminated in a chiaroscuro of blazing spotlights and the deepening darkness. "Do it. Pull it. Do I have to point my gun at you to ... do it?"

Twenty feet away, the officers shifted nervously. Some placed their fingers on the triggers of their shotguns and took aim at Savelkoul's chest. They were exhausted, on edge after the chase and long standoff. They knew only the sketchiest of details about the man in front of them, his blond hair short, his face twisted in grief and anger. Dispatchers had told them that Savelkoul had been diagnosed with post-traumatic stress disorder. They warned that he might have been drinking. Family members told police that Savelkoul had fled his home with six weapons, including a semiautomatic assault rifle and several hundred rounds of hollow point ammunition. To Megan Christopher, a trooper with the North Dakota Highway Patrol, Savelkoul's intentions seemed obvious. "Suicide by cop," she thought. "He wants to go out in a blaze of glory."

As it happened, Savelkoul's state of mind was of interest not only to the cops, but to some of the nation's top military officers and medical researchers.

More than 2 million troops have deployed to Iraq and Afghanistan since 2001. Tens of thousands have returned with a bedeviling mix of psychological and cognitive problems. For decades, doctors have recognized that soldiers can suffer lasting wounds from the sheer terror of combat, a condition referred to today as post-traumatic stress disorder. They also have come to know that blows to the head from roadside bombs -- the signature weapon in Iraq and Afghanistan -- can result in mild traumatic injuries to the brain, or concussions, that can leave soldiers unable to remember, to follow orders, to think normally.

Now it is becoming clear that soldiers like Savelkoul are coming home afflicted with both conditions, in numbers never seen before. Studies have estimated that about 20 percent of soldiers returning from Iraq and Afghanistan have suffered a mild traumatic brain injury while deployed. Of those, anywhere between 5 percent to nearly 50 percent may suffer both PTSD and lingering problems from traumatic brain injuries. It is an epidemic so new that doctors aren't even sure what to call it, let alone how best to diagnose and treat it.

Savelkoul and four of his comrades landed on the front lines of this confounding new conflict over the minds of America's soldiers when an Iraqi rocket exploded near their trailer in January 2009. By chance, a senior Army neuropsychologist was in Iraq at the time to conduct a study on the military's tools for diagnosing concussions. After learning of the attack, he persuaded Savelkoul and the others to enroll. The men became the first fully documented victims of "pure blast" concussions -- that is, mild traumatic brain injuries caused by the force of an explosion, rather than a secondary effect, such as slamming into a Humvee wall after a roadside bomb.

The concussions marked only the beginning of the men's problems. Aftershocks from the blast would ripple through each of their lives differently, mirroring the spectrum of psychic and physical outcomes that doctors have begun to catalog. Of the five men injured that night, three remain in the Army and are currently deployed to overseas war zones. One recovered quickly, though he continues to suffer occasional severe headaches. Two recuperated more gradually but complain of forgetfulness and problems concentrating. A fourth left the military, tired of the violence and still grappling with concussion symptoms.

Savelkoul struggled the most to return to the person he had been before. On that night last September, his troubles transformed from academic data point to terrifyingly real confrontation. All the Army's men, all its research, all its treatments, had failed to prevent the desperate showdown that would unfold on a deserted stretch of highway just south of the pinched hills of the Dakota badlands. Now the outcome depended on one distraught man and a half-dozen nerve-wracked police officers, trying to negotiate a battlefield of the mind that none of them -- no one in the world, really -- understood.

An Unremarkable Blast

In the violence of the wars in Iraq and Afghanistan, it was an unremarkable attack on an unremarkable day.

On the night of Jan. 16, 2009, several soldiers were hunched around a small television screen in a trailer at Camp Liberty, a sprawling base just outside of Baghdad. The men of Psycho platoon, Hell Raisers Battery, 1-7 Field Artillery of the famed 1st Infantry Division, the Big Red One, had arrived in Iraq from Fort Riley, Kan., in October 2008. They were on their second or third tours. After spending most of the day patrolling a nearby Iraqi village, they decided to unwind by playing "Call of Duty 4," a video game that allows players to act as U.S. Marines fighting in an unspecified Middle Eastern country. Subtitled "Modern Warfare," the game's scenes are harrowingly similar to the conflict in Iraq, with patrols down narrow streets of dun-colored buildings, sudden explosions and attacks by hidden enemies. "It sounds strange, but it's how we relaxed," said Staff Sgt. Derrick Junge, a muscular Illinois native with a shaved head and a fondness for reading Virgil, John Milton and Charles Dickens.

At about 8 p.m., the men heard the warning klaxon of the Phalanx, an antimissile system designed to destroy incoming mortar and artillery rounds by spraying bullets into the sky. The men continued playing "Call of Duty." Rocket attacks were common. The insurgents aimed so poorly that they rarely posed a danger. Seven minutes after the first warning, a second sounded. One man remembered that a fellow player, referring to the video game, called out "He's got a grenade!" Then, chaos enveloped the men.

Staff Sgt. James Hopkins, a Missouri native with a slight build, sharp face and a love of Red Vines candy, was sitting on his bed in a room next door to the rest of the men. He was talking to his wife on Skype. The blast force threw him to the floor. "It was just loud and thunderous. The living quarters actually shook. It was like if I were to stand next to the biggest Fourth of July explosion ever."

Spc. Jared Hollingshead was standing when the blast hit. The stocky Texan remembered "a bright flash of light, a very loud bang and everything goes blank after that. It was the most heart-wrenching thing you'll ever go through. It feels like your whole body clamps up. It's beyond words. It's utter terror."

Shane Fuller, then a corporal, was sitting with his back to the wall, listening to music on his laptop computer. "I just slumped over from the force of it," said Fuller, a Missourian who joined the Army after the lawnmower engine factory where he worked shut down. "All I could hear was ringing for 10 to 15 seconds."

An Iranian-made 107mm rocket had just slammed into one of the 12-foot-high concrete blast walls that protected the soldiers' housing compound, blowing a football-sized hole into the wall. Shrapnel, jagged and red hot, shredded the thin shell of the trailer, puncturing it with holes. Lights crashed down from the ceiling. Power went out. Fuller miraculously escaped physical injury, though shrapnel pierced the wall around him and ripped apart a Missouri State flag hanging above his head.

The men remember the next few minutes haphazardly, like a movie in which they duck in and out of the theater. In the dark and smoke that filled the trailer, several of them heard Savelkoul call out: "I'm hit, I'm hit!" A piece of metal from the rocket had burned his leg, making him the only soldier to suffer an external injury in the blast. Junge groped through the dark for a flashlight. Hopkins staggered out of his room to check on his men. Hollingshead grabbed his rifle. Fuller, who had blacked out, came to with blood streaming from his nose. Several ran to Savelkoul, dragging him to a nearby bunker.

Within minutes, combat medics arrived and took the men to a nearby medical clinic. They cleaned and bandaged Savelkoul's wound. They checked out Fuller but determined he had no injury. Though medics are supposed to check soldiers exposed to a blast for concussion, none of the men remembers talking about traumatic brain injury -- though all admit their memories were hazy. According to a doctor who reviewed their medical charts, none were diagnosed with concussions.

The men felt lucky. Nobody had died, nobody was seriously wounded, as far as they could tell. "I looked at it as though it wasn't a huge deal," Junge said. "You look at yourself and you say, nothing really happened to me."

By the next morning, Junge and several others went back on patrol.

As chance would have it, two weeks earlier, Lt. Col. Mike Russell -- then the Army's most senior neuropsychologist -- had landed in Iraq to begin a study of concussion at the behest of the Army's surgeon general. One of the first graduates of the neuropsychology program at Walter Reed Hospital, Russell had spent much of his career studying traumatic brain injury at Army hospitals and combat zones all over the world. He was something of an iconoclast in the military. Blunt-spoken and easily frustrated with bureaucracy, Russell decided the best way to find patients for his study was simply to hang out in military clinics, seeking blast survivors. He happened to hear about the rocket attacks at Camp Liberty and asked to examine Savelkoul and his comrades personally.

After assessing them at a field clinic on base three days after the blast, Russell concluded that five of the soldiers in the blast that night had, indeed, suffered mild traumatic brain injuries. The signs were obvious, Russell said, showing up clearly in the daylong battery of neuropsychology exams he performed. "When you work a lot with acute concussion, you actually kind of recognize even the look of a person who has been acutely concussed, which is kind of a dazed expression, a little bit unfocused, a little bit slow to respond," Russell said. "Several of them had significant gaps in their memory. And it wasn't clear how long they were unconscious. The last thing they remember is they were playing video games. The next thing they remember, they are outside the trailer in a shelter. Some minutes had actually passed where they weren't recording memories. That's post-traumatic amnesia. And that's your classic symptoms of a concussion."

For each of the men, Russell entered two diagnoses in their electronic medical records:

1. Concussion
2. Post concussive syndrome

The New Epidemic

War has always fueled innovation, helpful and horrible. Better body armor and battlefield medicine have helped soldiers survive injuries in Iraq and Afghanistan that would have proven fatal in previous conflicts. But the advances that have saved soldiers' bodies cannot protect their minds from insurgents' primary weapon, the roadside bomb. Blast waves penetrate through Humvee doors, bulletproof vests and Kevlar helmets, rattling soldiers' brains and altering cells and circuitry. Most recover quickly, but some suffer lasting damage to their cognitive abilities. At the same time, the terrifying experience of surviving such blasts haunts them, seeping out in violent nightmares and emotional outbursts.

Given the number of troops deployed, tens of thousands of soldiers, Marines, sailors and airmen may be suffering from this pernicious combination of PTSD and lasting problems from mild traumatic brain injury. They become, quite literally, different men and women than they used to be, a generation of warriors whose fight has shifted from external combat zones to invisible internal battlefields.

The issue has ignited debate in scientific and military circles, where much of the basic science remains in dispute. Are the two conditions related? If so, how? Does having a mild traumatic brain injury increase the chance of developing post-traumatic stress disorder? Or does surviving a terrifying event somehow make it more difficult for the brain to recover from a concussion? Doctors also struggle to tell the two conditions apart. PTSD and traumatic brain injury can produce similar symptoms, such as problems with memory and concentration. Yet both conditions escape detection by medical imaging devices, hindering diagnosis. Other conditions further complicate the picture. Besides PTSD and cognitive problems stemming from brain injury, soldiers also face chronic pain, missing limbs, vision, hearing and other physical problems. "It's very complicated," said Jennifer Vasterling, who has studied the issue and treated soldiers as chief of psychology at the Boston Veteran's Administration Hospital. "There are no simple scenarios."

Until recently, concussions were not even seen as particularly serious. Boxers boasted of returning to the ring after being knocked out. Soldiers in combat shook off feeling dazed and unfocused. Symptoms of concussions can include headaches, dizziness, difficulty speaking, memory troubles and sometimes balance and visions problems. Most people recover within four to six weeks. But for some, the symptoms can persist for months or even years. Civilian studies have found that between 5 percent and 15 percent of concussion victims endure long-term problems -- a condition formally known as post-concussion syndrome. Recent studies of athletes in the NFL and other sports have shown that repeated concussions can result in chronic traumatic encephalopathy, a condition associated with dementia and other Alzheimer's-like disorders.

Some researchers believe that soldiers' concussions may pose an even more complex medical challenge. Soldiers sustain their injuries in settings dramatically different from those encountered by athletes or car accident victims. Civilian concussions are typically caused by a physical blow to the head. But nobody is sure exactly how the brain is damaged in a blast concussion. Do blast waves rupture miniature blood vessels inside the brain? Does the force sever connections between neurons? Does it damage individual brain cells? Or does it simply slam the helmet into the head hard enough to injure the brain?

After the blast, soldiers face a different environment than typical concussion victims. No fans applaud as they rise from the field. Medics often can't rush them to the safety of a hospital right away. Instead, they remain on a hostile battlefield, fighting for their lives, the violence and rush of combat filling their brain with abnormal levels of chemicals such as adrenaline. Those left dazed, but not unconscious, experience a fear so fierce that it may simultaneously trigger post-traumatic stress. Paradoxically, patients who suffer severe traumatic brain injuries are less likely to develop PTSD -- perhaps because, knocked unconscious, they do not actually experience the horror unfolding around them.

"The scientific literature does not capture or mention the kind of patient that we are seeing," said Maria Mouritidas, psychology chair at Baltimore's College of Notre Dame, who worked with soldiers returning from the battlefield. "You can't compare this to a football game or a car injury. In a football game, if you go down, the game stops. On the battlefield, the game doesn't stop. Your survival depends on it."

For decades, the military has struggled to sort out the mysteries of concussions. In response to soldiers suffering head injuries during the Gulf War, the Pentagon and the Veterans Affairs joined forces to create what is today called the Defense and Veterans Brain Injury Center, a network of research and treatment clinics. But the wars in Afghanistan and Iraq dramatically expanded the need. Military doctors began noticing a wave of troops suffering brain injuries in blasts. In August 2006, the Armed Forces Epidemiological Board, responsible for monitoring health trends among troops, noted the growing number of head injuries. In a memo first disclosed by USA Today, the board warned senior Pentagon health officials that the military's medical system "lacks a system-wide approach for proper identification, management, and surveillance for individuals who sustain a TBI, in particular mild TBI/concussion."

However, it wasn't until the Walter Reed Hospital scandal of 2007 that the military dramatically increased attention to the so-called "invisible" wounds of war. The Washington Post revealed that officials at the hospital, the crown jewel of the military medical system, housed soldiers with brain damage in moldy hospital rooms, often ignoring their needs. The scandal caused an uproar in Congress and across the nation. Lawmakers passed legislation devoting more than $300 million in new research funds to brain injuries and PTSD. They ordered the military to conduct cognitive screenings of soldiers before and after deployment. President Bush created a commission headed by retired Sen. Bob Dole and former Health Secretary Donna Shalala to suggest recommendations to improve care for soldiers with PTSD and brain injury. In 2008, the Rand Corporation produced a groundbreaking report estimating that 19 percent of soldiers in Iraq and Afghanistan had suffered a probable traumatic brain injury, while another 18 percent reported symptoms of PTSD or depression. About 5 percent reported a combination.

Yet, despite the pressure and the growing numbers, the Pentagon's response was uneven, at best. ProPublica and NPR reported last year that the military continues to have problems diagnosing and treating brain-injured soldiers. The military's standard screens failed to catch as many as 40 percent of concussions, according to a study published earlier this month. Injuries weren't always noted in soldiers' medical files because of poor recordkeeping. In some cases, soldiers resisted admitting that they had sustained head traumas because of a desire to remain on the battlefield with comrades. In the command echelons, some high-ranking military officers dismissed the effects of mild traumatic brain injuries.

Col. Heidi Terrio, an Army doctor who has worked extensively with soldiers returning from the combat field, conducted a study published in the Journal of Head Trauma Rehabilitation that reported that 7.5 percent of combat soldiers returning from Iraq and Afghanistan showed three or more symptoms associated with post-concussion syndrome, with another 20 percent reporting one symptom. Terrio said her study showed that it was important to pay attention to soldiers with concussions. "Mild traumatic injury does not mean it's a mild problem," she said. "Mild doesn't necessarily mean mild consequences. One concussion may cause you to have lifelong problems. Most of the time it doesn't but it can."

The lack of clarity has frustrated battlefield commanders trying to navigate the debate in the middle of a war. "I don't feel comfortable on where the science is right now," said Gen. Peter Chiarelli, the vice chief of staff for the Army. "It's an extraordinarily tough nut to crack."

Chiarelli has worked relentlessly to change that, convening conferences of top neurologists and flying them to his wood-paneled office in the Pentagon's inner ring to hammer out possible treatments. He has encouraged researchers to find biomarkers to better diagnose brain injury. He envisions a system that, with enough data, could one day help commanders predict which soldiers were at greatest risk of committing suicide.

Although he acknowledges there is more work ahead, Chiarelli's temper flares at the suggestion that the Army is not trying hard enough to improve how it diagnoses and treats soldiers with brain trauma. He points to a directive issued last year that mandated rest periods for soldiers involved in blasts and thorough neurological examinations for those suffering three or more concussions. He also notes that the military has spent millions of dollars on research that has generated promising new technologies to identify and treat injuries related to PTSD and TBI.

"Our doctors are doing everything they can to come up with the best techniques possible to insure they get better at the initial diagnosis of these injuries," Chiarelli said. "But it is extremely difficult because the science is not as developed as it is with the mechanical nature of this war."

Call of Duty

Though the men of Psycho platoon returned to duty shortly after the explosion, several continued to experience aftereffects.

Hollingshead remembered stumbling across the base, unable to keep his balance on the white gravel that lined the ground between buildings. His ears rang constantly. He had difficulty keeping track of what his sergeants were telling him to do. "I just could not remember it. I'd ask three different times. It's a very unusual feeling, not being able to remember all of a sudden." Hopkins had similar trouble. "I just didn't feel right. I could barely walk a straight line," he said. "I was forgetting things, my attention span was shot, someone would be directly talking to me and I would not even really be paying attention. I couldn't recall or say back what they said to me. It was like I was paying attention but I wasn't gathering the information." Junge had splitting headaches, so he popped ibuprofen and Tylenol PM to help get to sleep.

In March, the Army held a ceremony to award the men combat action badges, given to soldiers who have attacked or been attacked by the enemy. For the wound to his leg, Savelkoul also received a Purple Heart, one of the military's most revered symbols of sacrifice, an honor dating back to George Washington. The other men, however, were turned down, even though Army regulations specifically list concussion as an injury deserving recognition. Hopkins was incensed. He began firing off appeals on behalf of himself and his men, with no success. "They don't consider [concussions] to be an injury that is going to stay with you for the long term," he said. "That's a big slap in the face."

For most of the men, some symptoms improved. Their balance got better, the headaches were not as severe -- a typical recovery from mild traumatic brain injury. But the symptoms did not go away entirely. Fuller's ears kept ringing. Hollingshead's headaches remained painful, sometimes disabling. Still, the men continued providing security details for senior commanders, patrolling villages, or protecting fuel and food convoys racing across the desert. "After we saw Dr. Russell, that was it. It was back to work," Hollingshead said. "Nobody ever came back to us to follow up."

Savelkoul was awarded another commendation, the Army Achievement Medal, for manning a gun truck and coordinating air support during a dangerous run between Baghdad and Al Hillah. That April, he was scheduled for a rest and relaxation break. He decided to go with a friend to Thailand. On March 20, he posted a message on Facebook: "on my way to Thailand !!!!" His sister, Angie, quickly wrote back: "have fun. Don't do anything stupid."

Savelkoul didn't reply.

The Farm Kid

Savelkoul grew up in North Dakota. His father was a car salesman, then a truck driver. When Savelkoul was getting ready to enter high school, the family enrolled him in a school in Glenburn, pop. 347, in far north-central North Dakota because their hometown school in Minot, pop. 36,000, was too big. Savelkoul played football and basketball for the Glenburn High Panthers. During halftime, he played trumpet in the high school band. At Christmas at his grandparents, Savelkoul and Angie, a flute player, would play mini-concerts. The family had its troubles, and Savelkoul's parents eventually divorced, but they stayed close.

Savelkoul loved hunting: deer, geese, coots. When he was 14, Savelkoul and his father Bruce drove out to the North Dakota badlands on a rainy, gray winter day. They hiked up a hill, getting soaked as they searched for game for hours. Suddenly, right in front of them, Bruce spotted a mule deer. It would be Brock's first kill. He started shaking uncontrollably as he tried to lower his rifle. Bruce gently crouched in front of him and had Brock lay the rifle across his shoulder, steadying it. Brock aimed, killing the deer with a single shot. It was a beautiful buck, its antlers tall and broad above its head. The mount, which won first place at a local trophy show in 1996, would hang on the wall of Bruce's mobile home, the first thing you see when you walked in the door. "He was a good kid, a very good kid," said Bruce, who is balding, with glasses. His pride in his son is obvious. "He was a farm kid. We had farm values -- scruples and values and respect."

After high school, Brock Savelkoul attended community college but soon dropped out. He was bored and unsure of what he wanted to do. He moved to Fargo, where he got a job with a fencing company. One day, he was on a job with an older man. He suddenly realized that he didn't want to spend the rest of his life building fences in Fargo. In February 2003, he signed up with the Army. He was assigned to Fort Riley. Six months later, Savelkoul headed to Iraq for the first of three tours.

During his tours, Savelkoul took on a number of different jobs. He was the gunner on a Humvee that patrolled the streets. He did foot patrols of villages. He took a course and began to operate Ravens, small surveillance drones used to fly above roads to make sure they were clear of bombs. Mike Krebsbach, a friend from basic training, said Savelkoul was a good, conscientious soldier. They were based in Baghdad, their quarters a palace that had once belonged to Saddam Hussein. At night, they would sit on the roof, staring over the boxy brown cityscape. Krebsbach, an atheist, would debate Brock, a Catholic, about God, life, the war. "We didn't talk much about the fear," Krebsbach said.

Two incidents seemed to affect Savelkoul, changing him. During his first tour, his unit began taking fire after turning down an alleyway. The men, novices to combat, fired back, seeking desperately to escape. All survived, but the incident shook them. "Everybody was tripping out," Krebsbach said. "We were acting like a combat infantry team, but with zero training. ... There was just a bunch of really scared soldiers."

During his second tour in 2005, Savelkoul was responsible for giving the OK after he scanned a route with the Raven and determined that there were no signs of IEDs, or improvised explosive devices. In an article for a base newsletter, he proudly told the reporter that his job saved soldiers' lives. "We're protecting them from the sky," he said. One day, however, a convoy driving down a route he had checked hit an IED. Details are unclear. Savelkoul rarely spoke of it. The bomb destroyed one of the vehicles. Several soldiers apparently died in the blast. "It blew the truck into nothing. You didn't even know it was a Humvee," said Krebsbach, who remembered seeing the vehicle after it was towed back to base. He said Savelkoul became sullen and withdrawn afterward. "It was hard to get him not to fixate" on that incident, he said.

Bruce Savelkoul remembers getting a solemn phone call from his son after the explosion.

"Dad, I'm responsible for those deaths," Brock told his father.

"No, you're not," Bruce responded, trying to console him. One of Savelkoul's commanders, who did not want to be identified because the Army had not authorized him to comment, said that he had looked into the incident and concluded that Savelkoul was not negligent in carrying out his duties.

In any case, the Humvee deaths weighed on Savelkoul, as did the failure of a brief marriage, which ended in divorce just a few months before he left Iraq in January 2006. To Angie, his sister, he seemed different. Although some family members had suffered depression, Savelkoul had never shown any signs of mental distress. "He wasn't his normal self. He was very quiet, withdrawn," Angie said. "It's like he wasn't there."

With straight blond hair and an open, honest face, Angie is the glue of the Savelkoul family, the little sister who keeps tabs on everyone. A labor and delivery nurse married to a plumber, she juggles crazy work hours with family crises and the kids' basketball games. Through it all, she made sure to communicate with Brock regularly. When he deployed to Iraq again in October 2008, she convinced him to open a Facebook account. They exchanged messages after the Jan. 16 explosion. Brock assured her he was OK.

That was why Angie got nervous when Brock didn't respond to her messages after he left for Thailand. "You need to write, call, something," she wrote. " ... gettin worried ... "

She had reason to be. Her brother had begun to fall apart.

Falling Apart

Photos taken of Savelkoul in Thailand show him acting as soldiers often do on leave, partying in bars, surrounded by friends and women. It's impossible to know exactly what happened, but about a week after his arrival, he began sending out strange messages: "I'm under special army training in Thailand ... It's crazy!!!" read one. Nothing in his military records indicates he received any training in Thailand. Friends remember getting nonsensical text messages on their cell phones. Bruce Savelkoul said Brock called him from Thailand in the middle of the night.

"'Dad, there are guys trying to kill me, Dad, you got to help me,'" Bruce said his son told him. "He was absolutely paranoid. I was 7,000 miles away. What could we do?"

At some point, U.S. Embassy and military officials picked up Savelkoul and transported him to Tripler Army Medical Center in Honolulu. There he was placed under lockdown and diagnosed as having suffered a psychotic breakdown.

After stabilizing at Tripler, Savelkoul was transferred back to Fort Riley. He seemed to pine for Iraq. "You guys have no clue how bad I want to be there!!!! It's just not the same without you guys," he wrote in a Facebook message in May 2009 to a fellow soldier still in Iraq. Officials at Fort Riley declined to comment on what kind of treatment he received. Savelkoul's military record shows that his condition wasn't improving. In August 2009, he was hospitalized a second time. In October, the Army barred him from possessing weapons. Savelkoul was diagnosed as suffering from post-traumatic stress disorder.

Post-traumatic stress disorder has its own controversial history. Accounts of soldiers suffering mental afflictions after exposure to war's horrors date back thousands of years. In Homer's Iliad, some have speculated that Achilles' blind rage after the death of a beloved companion is an early description of post-traumatic stress. During the Civil War, men who struggled to return to normalcy after the war were described as suffering from "soldier's heart." In World War I, it was called shellshock. World War II brought the name "combat fatigue." All generally described soldiers numbed and haunted, unable to return to battle -- or normal life.

Military commanders showed little tolerance or understanding during earlier eras. Gen. George H. Patton became infamous for slapping and publicly berating a soldier suffering from combat fatigue, calling him a "coward" and ordering him back to the frontlines. Patton was later forced to apologize.

The Diagnostic and Statistical Manual of Mental Disorders, the psychiatrist's primary diagnostic tool, did not formally recognized the syndrome until 1980, after thousands of veterans returned from Vietnam suffering psychological distress. Today, the diagnosis requires that troops meet a series of criteria. They include having faced a risk of serious injury or death; recurring nightmares or memories; and problems with sleep, anger and emotional control that last beyond a month. Researchers continue to debate the criteria and what happens inside the brain to trigger the disorder. Does a sudden rush of chemicals in the brain change fundamental pathways for dealing with stress? Do genes play a role?

Despite the questions, after a 30-year push by veterans and their advocates, PTSD has gained greater acceptance than post-concussion syndrome. Commanders and soldiers are reminded to watch for signs constantly during military training. Nearly all VA and military medical facilities offer some form of counseling for PTSD. By comparison, mild traumatic brain injury is the new kid on the block. At times, researchers have seemed to divide into factions, with PTSD advocates seeking to protect their gains and TBI advocates fighting to make advances. Charles Hoge, a retired colonel who published groundbreaking research on PTSD in Iraq and Afghanistan, has expressed skepticism publicly regarding the severity of mild traumatic brain injury. In an opinion piece in the New England Journal of Medicine, Hoge worried that overdiagnosis of lingering problems from concussion will create "illusory" demands for the military's medical system. "There tends to be camps. One camp is everything is TBI and the other is nothing is TBI," said Rodney Vanderploeg, director of the brain-injury treatment program at the Tampa VA, which specializes in treating soldiers with multiple traumas. "The truth is somewhere in the middle."

Savelkoul was suffering in that middle. In November 2009, the Army made a last-ditch effort to help him, sending him to a residential mental health program at a veterans' home in Yountville, Calif., called the Pathway Home.

It is hard to imagine a more idyllic location. Surrounded by the gentle brown hills of Napa Valley, the sprawling campus of Spanish-style buildings has towering redwoods and lush green lawns. Fred Gusman, a nationally prominent expert in PTSD who recently retired from the Department of Veterans Affairs, established the program in January 2008 for Iraq and Afghanistan veterans. The intensive, six-month program is designed for the hard cases, the troops and veterans who have had an especially difficult time recovering in traditional military settings, where therapy can be haphazard and uncoordinated. At the Pathway Home, teams of doctors and clinicians strive to take a comprehensive approach to care, coordinating treatments for psychological trauma, chronic pain and other issues, such as alcoholism. Patients have encounter groups. They go fly fishing and hiking.

Savelkoul, Gusman remembered, had symptoms similar to scores of patients that have gone through his program. He suffered nightmares, severe depression, trouble sleeping, headaches. "He's not unique in what we see," Gusman said. Savelkoul struggled to adjust to the program. Sometimes he would participate. Sometimes he would withdraw, apparently not convinced that he needed help and uncertain whether he wanted to remain in the Army. "There is anger, fear and shame. A lot of people wonder why they are in this treatment and others are not. They get stuck like that," Gusman said.

After about two months in the program, Savelkoul wandered off campus -- which is not closed -- and somehow made his way to Sacramento. Bruce Savelkoul got a call a short while later. Brock told him that he was back in Baghdad, surrounded by thousands of people. At about the same time, Gusman got a call from a staff member. Savelkoul had been found in the Old Town section of the city, a tourist area near the Sacramento River. He had been drinking and was having a panic attack, they told Gusman. Gusman sent a van to pick him up and transport him to Travis Air Force Base. Eventually, Savelkoul was sent back to Fort Riley. Gusman said Savelkoul was not yet ready for his program and that the military did not aggressively pursue other treatment options: "The problem in this country is that we haven't accepted the hard reality that we can train people to be in a war. ... But we can't train somebody in how they're going to respond."

For the military, it was the last straw. Staff Sgt. Brock B. Savelkoul was honorably discharged from the Army on March 31, 2010. He had served two years, three months and four days in Iraq. His awards included the Purple Heart, the Army Commendation Medal and the Army Achievement Medal. He was placed on temporary disability due to post-traumatic stress disorder. He was ordered to be re-evaluated in six months.

Savelkoul was going home.

The Others Struggle

In September, just before Savelkoul was shipped off to California, the rest of Psycho platoon returned from Iraq. They began to split up. Junge was transferred to Fort Campbell in Kentucky. On a test he took shortly after getting back, a screen given to all soldiers to check for potential brain injury and mental health problems, Junge had filled in "Yes" for every question relating to traumatic brain injury. Positive answers are supposed to trigger an evaluation by a medical professional. But nobody at the local TBI clinic ever examined Junge.

Junge, his wife Holly and their kids moved to a modest home with two magnolia trees in the front yard in Clarksville, Tenn., a short distance from their new post. As they settled in, Holly began to notice changes. Junge would snap at the kids, something he had never done before. He started building a tree house in the front yard but never quite finished. Before joining the Army, Junge had been an air force mechanic on the B-2 stealth bomber, one of the most complicated pieces of machinery ever invented. Now he struggled to fit together the pieces of a trampoline in their backyard. Holly, a nutritionist with a soft face and brown hair, grew worried. "From day one, he was a different person," she said. "He was very irritable. He doesn't sleep well. He forgot things, little things, but kind of annoying."

One day, the couple's 10-year-old daughter asked Holly, "Why is Daddy so mean to you?" Recalling the question, Holly began to cry. "Everything was wonderful. Not that's he's not now," she said, wiping tears from her face. "But it's different."

Junge said he never considered his troubles serious enough to go see a doctor. Nobody had ever ordered him to seek counseling. He was focused on his men, he said, and getting ready to redeploy to Afghanistan. "I just don't deal with stuff like I used to," he said. "I guess you could say I used to be a different person. It kind of sucks. But it's where I'm at and you work with it the best you can."

Upon his return, Hollingshead had a mental health examination at a VA hospital in Shreveport, La. He was hoping to begin PTSD counseling, but he left the Army before treatments could begin. Hollingshead said he was simply tired of the violence and bloodshed. "I wanted to be done," he said.

He eventually moved with his wife, Lena, to be near his family in Marshall, Texas, on the far eastern edge of the state. They found a small home surrounded by piney woods. He began taking classes to learn how to become a lineman for a power company but struggled to find a job. During his time in Iraq, he had lived through two bomb blasts, the one in January 2009 and an earlier one on his first tour. Now he would wake up in the middle of the night, thrashing his arms and legs. When he went to a July 4 fireworks show, he panicked at the explosions, gripping Lena's arm so hard that it left marks. "I'm glad this military time is over," she said. "It took its toll. It took its toll."

Hopkins and Fuller stayed at Fort Riley. Both began to see therapists at the base's traumatic brain injury clinic. Hopkins went four times a week. He did exercises to help improve his memory. He got a handheld computer device to help him make lists. He practiced reading. His wife, Brianne, labeled the closets in their home to help him remember where to put things. At first, she said, it was frustrating. Hopkins would forget things that she had asked him to do. The couple has five kids. "Sometimes I joke about having an extra child because we have to repeat ourselves to the kids to remind them to do things." After about two months, Hopkins took a new battery of neuropsychological tests. "They pretty much cleared me at that point," Hopkins said. "They asked me how I felt, and I told them I felt pretty much 100 percent better besides the headaches and things of that nature."

Fuller had a similar experience. The ringing in his ears continued even after he got home. He got prescription-strength medication for his headaches, which came less frequently but still hit him hard. His wife, Hillary, who had known him since the 6th grade, noticed that he would start a sentence and then suddenly stop talking, as if frozen. He would forget to do small things, like button his shirt. He was irritable and angry. But slowly, she said, he improved. By the spring of 2010, about six months after his return, most things had returned to normal, she said. "I've dealt with him coming back from Iraq before without any complications. This was just a little different," she said.

"I think that had a lot to do with the rocket attack."

Seeking Help

Savelkoul returned to Minot and moved in with his father, into a 16-by-80-foot mobile home on the southern edge of town. On April 3, he posted on Facebook, referring to his profile picture. "Home!! Great to be home with family!!! Guess I should take that Army pic down and put up a civilian pic ... errr don't want to but that's what I am now." He tried to continue psychological treatments, but Minot is 271 miles from the nearest Veterans Affairs hospital. He started to make the drive several times but would get spooked when going under overpasses, often the site of insurgent attacks in Iraq. Savelkoul also sought help at a local VA clinic in Minot, but his counselor left. He tried going up to the Air Force base north of town but didn't feel like he fit in.

Savelkoul's troubles in finding treatment were not unusual. The majority of VA patients are older and served in the Vietnam War. The VA has struggled to figure out how best to adapt to the newer, younger veterans now seeking mental health counseling and therapy. The issue is especially acute in rural areas.

Savelkoul's family noticed how much he had changed. He couldn't remember birthdays, anniversaries or even the date his mother had died. On a shopping trip with Angie, he didn't recognize the house where they had grown up. He seemed uncoordinated and had trouble playing catch with his nephew. Trips to the Minot Zoo and a Minnesota Twins baseball game ended in disaster when he grew panicked at the crowds around him.

"All these people are dead. Why should I be alive? I'm lost. I'm confused," he would tell Angie.

The family felt confused, too, and unsure what to do. As a nurse, Angie was upset at all the different medications Savelkoul was taking -- antidepressants, antipsychotics, mood stabilizers, sleeping pills. "They weren't doing anything for his symptoms," Angie said. "Every doctor he'd see, they'd give him something different. ... You get that many meds, they interact with each other. They can be dangerous."

"We wanted him home because we thought he needed family," Bruce said. "He was not ready for the real world. ... We didn't know how to handle him."

On the evening of Sept. 21, Brock sent Angie and Bruce a text message. It read: "I love you guys more than anything. Never forget it. I can't do this anymore."

Bruce raced home. On the stove, Bruce found a grocery list that Brock had begun with the word "butter" at the top. After that, Brock had scrawled a note. It read: "No hope for me. Love you so much."

A licensed gun dealer, Bruce found that Brock had ripped open boxes containing guns that he planned to sell. Missing was a DPMS AR-15, an assault rifle similar to the M16 used in Iraq, two hunting rifles and three handguns. Also gone were two 30-round magazines and several hundred rounds of hollow point ammunition.

Bruce went to Brock's room and found he had destroyed his laptop computer. He also had smashed open a small, wooden case that hung next to his bed. It contained photos, mementos and awards from Iraq. He had taken out his Purple Heart.

Bruce knew he had no alternative. He called the police on his own son. "I didn't know what to do. I thought that he was gonna hate me forever, but I really had to call the cops," he said.

The hunt for Savelkoul had begun.

The Chase

At around 6:20 p.m. on Sept. 21, Savelkoul walked into a convenience store called the Kum N Go in Watford City, a small town about 120 miles west of Minot. Police records say that he pointed a rifle at one of the patrons and asked, "Do you want to die?" Then he fled the store.

He headed south down Highway 85, a narrow, two-lane road undergoing construction repairs. A Watford City police cruiser heard the call about the altercation at the Kum N Go, spotted Savelkoul headed out of the city and turned on his lights and siren.

Savelkoul gunned his Tacoma through the narrow gravel beds of the construction zone. He kept going faster and faster, 60, 70, 80, until he hit 105 miles an hour, police records say, flying down the arrow straight road, across the river, toward the North Dakota badlands.

Back home, Angie and Bruce had told a friend from the local police department about Brock's past, that he was a veteran suffering from PTSD, and heavily armed. The friend relayed the information to the police chasing Savelkoul. As the chase progressed, the friend would call Angie and Bruce to give updates. In the background, they could hear the dispatchers talk as more and more police officers were called in to stop Savelkoul.

Bruce Savelkoul realized that his son was driving toward the same area where they had stood together 15 years earlier, to shoot his prized deer. "I don't know that anybody can say why somebody wants to kill themselves," Bruce said. "But that was one of the favorite places he'd been in his life. Maybe a person wants to go to a favorite place to die. That's what I think. I think his mission that night was to die."

The chase, captured on video cameras mounted on Highway Patrol cruisers, unfolded like a movie. When a patrol car attempted to block Savelkoul's route, he pulled off the highway, bouncing through high grass, blasting through a barbed-wire fence. A few minutes later, he roared back on the highway. Finally, out of gas, he pulled over on a farm road about 15 miles from the hunting grounds where he shot the deer. Within seconds, he was surrounded by sheriff's deputies, police officers and highway patrol troopers. They began yelling: "Drop the gun, drop the gun!"

The standoff was just beginning. Over the next two hours, Savelkoul paced, smoked, brandished weapons and even shot a round into the back of his pickup. On several occasions, Savelkoul disappeared from view behind his truck. Officers worried that he was attempting to sneak through the darkness to get behind them. At perhaps the most tense moment of the standoff, he came within feet of one of the patrol cars. Raising his 9-mm handgun to his side, he begged someone to shoot. "Go ahead, shoot me!" he yelled. As the officers held their fire, he reassured them he would not shoot first. "You already ... know that I won't ... hurt, I will not ever shoot, a law enforcement agent," he said. "This gun will go to my head before it will go to you. I guarantee it."

Through it all, one officer, Megan Christopher, talked to Savelkoul nonstop, working feverishly to save his life. Christopher had joined the North Dakota Highway patrol only two years earlier. With high cheekbones and bright blue eyes, she had already made her mark, helping chase down four fugitives featured on an episode of "America's Most Wanted." In her brown trooper's hat and carefully pressed uniform, she could pass for a real life version of the cop Frances McDormand played in the movie "Fargo."

On the evening of Sept. 21, she had been sitting down to dinner when the call came in. She and her commander raced to join the chase. When Savelkoul finally ran out of gas, Christopher was one of the first on the scene.

Although she was a junior officer with no real training or experience in crisis negotiation, she was the first officer to use her patrol car megaphone to talk with Savelkoul. Savelkoul seemed to respond to Christopher, the only woman on the scene. "I tried to put myself in his shoes and empathize," she said. "I think my voice was softer and not expected."

Christopher tried anything she could think of to convince Savelkoul to surrender. When she learned his first name, she introduced herself. "Brock," she said. "My name is Megan." When Savelkoul took out a tube of Chapstick, Christopher needled him. "What kind of Chapstick was that? I need some," she said. "My lips are really dry now. I've been talking a lot." When he turned up the radio, Christopher tried to sing along. "La, la, la. It's time for Karaoke," she joked. She appealed to his past. "You sound like you're pretty proud of the medal that you have," she said, referring to his Purple Heart. "I appreciate everything that you've done for your country, for me and my country." She urged him to think of his future. "You have a lot of people who want to help you," she said. "What you're doing is not fair to anybody. And especially not to you."

With a cell phone in one hand to communicate with one of Savelkoul's friends and a microphone in the other, Christopher never stopped the chatter and never left her position crouched behind the door of her patrol car. The cold cramped her hands. The sleet soaked her uniform. Over and over, she made a simple, emotional plea: She wanted to meet Savelkoul in person, alive and well. "Brock, I'd like to meet you. Put the gun down so we can meet," she said.

Finally, at about 9:30 p.m., more than three hours after the chase began, Savelkoul aimed his gun toward the open prairie and fired a round. Then, the videotape shows, he walked toward Christopher. After she promised to give him a cell phone if he put down the gun, he placed it at his feet. Christopher walked toward him, holding the cell phone in front of her, her own weapon holstered. Her voice broke as she neared him. "I'm kinda new at this. Sorry," she said. "I think I'm going to cry."

Suddenly, Savelkoul turned toward her. Two coiled, white wires unspool through the night air. Another officer, believing that Savelkoul was turning to attack, had fired his Taser, a weapon designed to shock a person into incapacitation. Savelkoul stiffened and fell to the ground. Police officers ran toward him from all sides, their knees on his back, arms, legs. They handcuffed Savelkoul. Christopher walked toward him and knelt. She put her hand to his cheek.

"I'm Megan," she said, "I'm glad I get to meet you."

New Mission

In November 2009, Lt. Col. Mike Russell presented his initial findings involving Savelkoul and nearly 300 other soldiers at the annual meeting of the National Academy of Neuropsychology. His conclusion: The primary test the Army was using to evaluate whether soldiers had suffered concussions was "only slightly better than a coin toss." Another tool being deployed was even worse. The tests were fixable, Russell told the gathering, but the Army was still a long way from diagnosing and treating soldiers like Savelkoul and his buddies. "We did not design our health care system for mild traumatic brain injury," Russell told the audience. "There are a tremendous number of people who have concussions ... meet the diagnostic criteria for mild traumatic brain injury, that never seek professional attention."

Russell's work featured prominently in the Army's Surgeon General's testimony before Congress on problems at the military's top medical center for brain injury. The Army is working now to develop better tests. Russell has recently launched a follow-up investigation in which he hopes to re-evaluate the soldiers in his original study.

In October 2010, a few months after Congress learned of Russell's results, Staff Sgt. Derrick Junge redeployed to Afghanistan. Before he left, he visited a doctor for the first time since the January 2009 blast, discussing his troubles with short-term memory and concentration. The doctor recommended that he visit Fort Campbell's clinic for traumatic brain injury. Junge declined. "I told them to hold off. I didn't want it to keep me from deploying," he said. Last month, Junge survived another roadside explosion while on a convoy with his men in Paktika, a remote province in southern Afghanistan. He was checked by a medic, who cleared him to return to duty, said his wife, Holly. Junge, who has only occasional access to e-mail, could not be reached for details. Holly said that her husband continued to have problems with his memory. On a recent break, he suggested renewing their wedding vows. He asked her to write down his request in case he later forgot making it. "It's worrisome," she said. "I told him that as long as he doesn't forget my name and the kid's names, we're OK."

Hollingshead is still seeking steady work. He and his wife are looking forward to the birth of their first child this summer. Memories of the blast still haunt him, he said. "We weren't missing an arm or a leg or a finger. We weren't bleeding. But the brain is just as important. If it's injured, it's injured. I'm going to have these issues for the rest of my life," he said. Hollingshead is still waiting for an appointment to see a doctor at the nearest VA hospital, which is 45 minutes away. He has already signed up to be in Russell's follow-up study. "I'd like to get an MRI and do whatever. It'll help soldiers down the line later on. What they find out in me might help somebody else later on. Anything that I can do to help the future, I'll do it."

Fuller, now a sergeant, and Hopkins have both redeployed to Iraq. Fuller, who has had a ringing in his ears since the explosion, said he is returning to the war zone convinced of the severity of even mild traumatic brain injuries. "TBI effects different people in different ways. It's critical that this is discussed. It's a serious injury, even though you can't see it," Fuller said. A few days after his arrival, he visited the trailer where the January 2009 blast had occurred. It still stands, the shrapnel holes patched with white caulking.

Prosecutors charged Savelkoul with three felonies and a misdemeanor. His sister, father and a local veterans' advocate lobbied North Dakota's governor and other officials, urging that he get treatment instead of remaining in jail. At a court hearing in October, the judge agreed to release Savelkoul on a $10,000 bond, as long as he attended a VA treatment program.

In December, Savelkoul was committed to a psychological lockdown ward at the Fargo VA hospital as he waited for an opening at the nearest VA residential treatment program. He was the only patient on the ward. His room had a single plastic chair and a single bed. There was nothing sharp. The bathroom door was a piece of foam covered in soft beige fabric. He looked hollow, bewildered and tired. He said that he could not recall details of the poli