Earlier this week, federal prosecutors and defense lawyers wrapped up opening arguments in the Danziger Bridge murder trial—the highest profile of nine criminal cases against current and former members of the New Orleans Police Department for shooting unarmed civilians after Hurricane Katrina.

This incident was one of several investigated by ProPublica and our partners at the New Orleans Times-Picayune and PBS "Frontline" as part of the series "Law & Disorder."

On Sept. 4, 2005, about a dozen NOPD officers arrived at the Danziger Bridge in response to a 911 call about a fellow officer under fire. The officers allegedly began spraying bullets, killing two civilians and severely injuring four more. None of the civilians shot were armed, according to federal prosecutors.

In 2008, an Orleans parish judge tossed out a state case against seven officers involved in the bridge shootings, saying prosecutors mishandled grand jury evidence. When that case collapsed, the federal government opened its own investigation into the incident.

The prosecution's case is expected to rely heavily on the testimony of five former NOPD officers who have already pleaded guilty to planting evidence, fabricating witnesses and holding secret meetings to get their stories straight.

The trial comes at a pivotal point. After years of intense scrutiny, the NOPD is facing a steady stream of convictions and investigations. The Danziger Bridge shootings and the murder of Henry Glover have been the two major focal points for alleged police misconduct. In December 2010, three officers were convicted for killing Glover and burning his body in another attempted cover-up. (One conviction has since been set aside.) In March 2011, the Justice Department released a damning report on the NOPD, finding that the department needed a "complete transformation."

The report said officers "systemically misclassified" rape cases to sweep them under the rug and noted a sharp disparity in the high rate of arrest of blacks compared to whites. The Justice Department also found that officers routinely encouraged each other to use force as retaliation, even with handcuffed arrestees, and supervisors did not investigate the few violations reported. The NOPD has not found a single policy violation in an officer-involved shooting in the last six years, despite federal findings that violations had occurred.

The yearlong investigation was launched at the request of Mayor Mitch Landrieu. Local and federal officials have said they expect the system-wide probe to lead to a consent decree and monitoring of the department's reform efforts by a federal judge.

The Danziger Bridge shootings trial may shed more light on NOPD's inner workings and, as with the Glover case, break the history of silence among officers and supervisors. The lead prosecutor for the Justice Department framed what happened at the bridge as a case of "Shoot first and ask questions later," according to a New York Times story. She called as her first witness Susan Bartholomew, a victim who had to raise her left arm for the oath because her she lost her right arm as a result of the bridge shooting.

Defense attorney Frank DeSalvo ridiculed the DOJ case as a work of fiction, "better suited for a John Grisham novel," the Times-Picayune reported. He said the accused officers had served the city at a time when others fled in droves and should be praised, not prosecuted.

David Benelli, a retired NOPD officer, echoes this sentiment in "What Happened on the Danziger Bridge?" a "Frontline" video on the case. "During the Katrina days, we weren't living in the real world," Benelli said. "We were living in a Holocaust. We were living in a situation that no other police department had to endure."

For those interested in a recap of the shooting and the subsequent legal case, see this Times-Picayune diagram and timeline.