An unaccompanied migrant girl from Guatemala with a pre-existing medical condition died in U.S. custody earlier this week after crossing the southern border in May, according to information provided to Congress and obtained by CBS News.

The 15-year-old migrant was hospitalized throughout her time in the custody of the Department of Health and Human Services (HHS), which cares for unaccompanied children who lack a legal immigration status.

At the time Customs and Border Protection (CBP) transferred the child to HHS custody in May, she was already hospitalized in a pediatric intensive care unit in El Paso, Texas, due to a "significant, pre-existing illness," according to the notice sent to congressional officials.

After the child's health began to worsen last week, she was pronounced dead on July 10 as "a result of multi-organ failure due to complications of her underlying disease," the notice said. Officials noted that the girl's mother and brother were with her at the time of her death.

In a statement Tuesday, HHS confirmed the girl's death. "Our heart goes out to the family at this difficult time," the department said. "(The Office of Refugee Resettlement) is working with them to provide comfort and assist with arrangements as appropriate."

The Guatemalan teen's death marks the fourth death of an unaccompanied migrant child in HHS custody this year, though some of the children had serious, pre-existing conditions, including terminal illnesses.

In March, a 4-year-old Honduran girl died after being hospitalized for cardiac arrest in Michigan. The girl had been in a medically fragile state throughout her years in HHS custody, according to people familiar with the case and a notification to Congress obtained by CBS News.

In May, HHS disclosed the death of a 17-year-old Honduran boy who was being housed in a shelter for unaccompanied minors in Florida. Officials at the time said the death likely stemmed from an epileptic seizure. The following month, a 6-year-old child who had been evacuated from Afghanistan following the Taliban takeover of that country in 2021 died in HHS custody. The boy had a terminal illness.  

In addition to the child deaths in HHS custody, another migrant minor, 8-year-old Anadith Tanay Reyes Alvarez, died in Border Patrol custody in May. While CBP has continued to investigate the death, preliminary government reports have found that Border Patrol medical contractors repeatedly declined to take the sick Panamanian-born girl to the hospital, despite multiple pleas from her mother. The agency also detained the family for over a week, even though internal rules generally limit detention to 72 hours.

U.S. law requires Border Patrol to transfer unaccompanied migrant children to HHS custody within 72 hours of processing them. HHS is then charged with providing housing, medical care, education and other services to these children until they turn 18 or can be released to a sponsor in the U.S., who is typically a relative.

As of earlier this week, HHS had 6,214 unaccompanied migrant children in its network of shelters, foster homes and other housing facilities, government figures show. The vast majority of children referred to the agency are teenagers who fled poverty and violence in Central America's Northern Triangle. 

After peaking at 10,000 in May, daily illegal crossings along the U.S.-Mexico border have plunged in recent weeks. The Biden administration has attributed the dramatic drop in unauthorized border arrivals to its efforts to expand legal migration channels while tightening asylum rules for those who don't use those programs.

Camilo Montoya-Galvez

Camilo Montoya-Galvez is the immigration reporter at CBS News. Based in Washington, he covers immigration policy and politics.

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