They were as young as 10 months, as old as almost 18.

About one-third of the children who ended up in Chicago came from Guatemala. Others had fled Brazil, Honduras, El Salvador, Belize, Romania and India. All had at least one parent locked up, often hundreds of miles away.

Months after the plight of children separated from their parents under the Trump administration’s zero-tolerance immigration crackdown sparked outrage, prompting a reversal of the policy, those children’s identities and experiences in detention remain largely unknown.

But ProPublica Illinois has obtained confidential records about the 99 children sent to Illinois shelters run by the nonprofit Heartland Human Care Services, which has a federal contract to house immigrant children at nine facilities in the Chicago area.

The records are part of a larger set of documents that shed light on the inner workings of the country’s secretive detention system for children, revealed in a ProPublica Illinois investigation last week.

Similar to minors who arrive in the United States on their own, the children separated from their parents had often fled danger and arrived at the shelters scared and confused. But they tended to be younger and more traumatized by their detention. Suddenly alone, the children agonized over missing their parents and acted on their anguish by threatening to harm themselves or others, the files show.

Seven of the separated children in Chicago still haven’t been reunited with their families.

One of them, a 12-year-old boy named Erick — in custody nearly four months after immigration officials took him from his father — became so depressed that he was admitted to a psychiatric hospital for a week, diagnosed with adjustment disorder, according to the records.

Since he was placed in Heartland’s care in May, Erick has been put on at least three medications to control his depression, aggression and emotional outbursts, has had trouble sleeping and has fought with other children and staff, according to the documents.

In June, an 11-year-old boy from Guatemala, housed at a Heartland shelter in suburban Des Plaines, cried inconsolably and said, “I want to die here,” the records show. Employees there told him “he needs to live to see his family.”

A 12-year-old girl from Romania reported she felt “as though she would die without her dad.”

And a 13-year-old from Brazil felt bad he didn’t know information about his mother. Their first call didn’t come until nearly a month after they were separated.

Heartland officials said the Trump administration’s zero-tolerance policy has caused “incalculable harm” to children, leaving the organization with the job of “picking up the pieces of the administration’s very destructive policies.”

A federal class-action lawsuit filed by a coalition of lawyers last week asks that the government pay for mental health treatment for children separated from their parents, saying the “traumatic event” has caused “severe and often permanent emotional and psychological harm.” Psychiatrists and pediatricians had urged the government to end the policy, arguing it would lead to anxiety, depression and developmental delays.

“The damage inflicted was not something that went away because of the reunification,” said Jesse Bless, one of the attorneys who filed the lawsuit, who has represented children housed at Heartland’s shelters. “We are starting to see signs that there could be long-term effects.”

Heartland Human Care Services is part of a larger nonprofit organization, Heartland Alliance, that focuses on a range of human rights issues. The group houses about 3,000 immigrant children a year in the Chicago area. Children separated from their parents have been held at three shelters in Chicago — in Englewood, Bronzeville and Rogers Park — and two in Des Plaines.

The documents obtained by ProPublica Illinois include rosters with demographic information about the children, including 39 who arrived during one week in late May, at the height of the crackdown.

Heartland employees closely tracked the children, detailing how well they were coping and making daily notes on efforts to reunite them with their families or connect them by phone. The agency was under pressure to move quickly as the government faced a court-ordered deadline to reunite about 2,600 children held in shelters across the country. As of last week, more than a month after the July 26 deadline, about 400 remained separated from their families.

Heartland officials said some of the seven children in its care who have not yet been reunited with their parents face an “uncertain future.” Their cases are among the most challenging because their parents have been deported or remain in detention, or no sponsor — typically a relative or family friend — has been identified to take them in.

The federal Office of Refugee Resettlement, which oversees the unaccompanied minor program, has the final say on when a child can be released. Federal officials have said they take multiple factors, including safety, into consideration before placing a child and that the process begins as soon as a child is in custody.

The records show how difficult it has been to reunite families, a task made even more challenging because the government had no system to do that. In case notes, Heartland staffers routinely said they found it hard to reach U.S. Immigration and Customs Enforcement employees to learn a parent’s whereabouts.

When Heartland workers did speak with ICE employees, the agency sometimes couldn’t locate parents, or, by the time they did, the parents already were being moved to a different detention facility. Some parents were scattered across the country in detention centers from Georgia to Arizona. Others were deported.

One Heartland caseworker made repeated efforts to connect a 17-year-old Brazilian boy with his father. The teenager arrived at a Heartland shelter on June 11. His caseworker asked ICE on June 14 where his father was being held and followed up twice without getting a response.

Finally, on June 29, ICE officials said they could not locate the father.

It wasn’t until July 3 — three weeks after the teen arrived in Chicago — that he spoke with his father, who was in detention. The boy was released July 24 to ICE’s custody with his father.

While most separations occurred during a six-week crackdown from April to June, the Heartland records make clear that family separations were happening long before the policy was formalized and came under public scrutiny.

One boy from Brazil, for example, was 13 when he was separated from his father when they were apprehended after crossing the U.S.-Mexico border in July 2017.

The father was sent to a detention center in El Paso, Texas, and deported in December. The teenager was sent to Chicago, where he was detained for at least 400 days. He remained in Heartland custody as of late August. He is now 15.

Destinee, an 11-year-old girl from Guatemala, arrived at a Heartland shelter on May 22 and was released in late June to live with relatives in South Florida. As of last week, her mother remained in detention in Texas.

In a recent letter to her mother, Destinee described her loneliness during her five weeks in Chicago.

“I cried during the nights in the shelter,” she wrote in Spanish. “I spent all night crying, asking God for us to be together again.”

The girl’s aunt told ProPublica Illinois she has filed reports alleging abuse by Heartland employees with child welfare authorities in Illinois and Florida and also with the federal government, saying the girl was given medication that heavily sedated her on the flight from Chicago to Miami. The Illinois Department of Children and Family Services has opened an investigation into the allegations. Heartland declined to comment.

The parents of Erick, the boy who required psychiatric hospitalization, have been asking for months for him to be sent home to Guatemala, according to caseworker notes. The parents provided a notarized letter with the request three months ago, the records show, and Erick’s father told the Los Angeles Times that immigration officials tricked him into signing documents that he believed allowed his son to return with him.

A spokeswoman for the National Immigrant Justice Center, the legal aid branch of Heartland Alliance that has been working on Erick’s case, said he was supposed to leave for Guatemala in late August, but a judge delayed his return because of a court order barring children from being deported until their immigration asylum cases are heard.

“The delay was heart-wrenching,” NIJC spokeswoman Tara Tidwell Cullen said, “and illustrates the level of chaos and uncertainty that persists surrounding the government’s reunification efforts.”

Erick has been cleared for release and is scheduled to fly home this week. This time, his lawyers said, they hope he will be on the flight.