After a sixteen-year-old Guatemalan boy died in Border Patrol custody in May, officials gave a basic account of what happened. Carlos Gregorio Hernandez Vasquez crossed the border alone near Weslaco on May 13, and was then held at a processing center for unaccompanied minors in nearby McAllen for six days until falling ill on May 19. That day, a nurse practitioner found that he had a 103-degree fever, and he tested positive for the flu. He was prescribed Tamiflu and transferred to the Border Patrol station at Weslaco. Hernandez died the next morning.

Now an autopsy report obtained by Texas Monthly provides new details about the death of Hernandez, the fifth Guatemalan child to die since December after being taken into Border Patrol custody. Conducted by Dr. Norma Jean Farley, a contract forensic pathologist for Hidalgo County, the autopsy concludes that Hernandez succumbed to the flu, complicated by pneumonia and sepsis, on or near the toilet of his South Texas Border Patrol cell.

He was fed at 2 a.m. May 20, and agents reportedly checked on him every hour, according to the autopsy. But some time later, in a video that Farley apparently reviewed, Hernandez “is seen lying on the floor, vomiting on the floor, and walks over to the commode, where he sits and later lies back and expires.”

The exact time of Hernandez’s collapse isn’t known because, as the report notes without explanation, “the time on the video is incorrect.” Regardless, the boy was found at 6 a.m. that same morning and declared dead twelve minutes later.

The circumstances of Hernandez’s death strengthen the criticism of Border Patrol’s handling of sick children. The agency is required to transfer unaccompanied children to the Office of Refugee Resettlement within 72 hours, but officials have acknowledged repeatedly failing to meet that requirement this year, including in Hernandez’s case. Hernandez was also never taken to a hospital despite the apparent seriousness of his illness and the fact that the flu has claimed the lives of two other Guatemalan children in Border Patrol custody in the last six months.

A veteran forensic pathologist who reviewed Hernandez’s autopsy, as well as the three other autopsies available for migrant children who died in custody, said she was alarmed at the conditions the children were kept in.

“Prolonged custody of mixed groups of migrants from different regions in close quarters increases the likelihood of transmission of respiratory pathogens such as influenza,” said Dr. Judy Melinek, a board-certified forensic pathologist in San Francisco and CEO of PathologyExpert Inc. “In my opinion, there needs to be a public health audit of the policies and conditions in these migrant camps and a forensic review of all migrant deaths.”

Dr. Jonathan Winickoff, a professor of pediatrics at Harvard Medical School and MassGeneral Hospital for Children, pointed out that flu deaths are “fairly rare events” for children living in the United States—a rate of about one death per 600,000 children. By contrast, Customs and Border Protection held 230,000 children between October and May and three of them died of the flu, though Winickoff noted that children in migrant detention are also at higher risk than the general population of contracting influenza and other infectious diseases in the first place.

CBP did not respond to specific questions about Hernandez’s care. However, a spokesperson said people with flu “are handled as appropriate, depending on the specific circumstances. Children with flu may be diagnosed and treated on-site by CBP medical personnel or may be referred as appropriate to the local health system for diagnosis and treatment.”

All of the children who’ve died since December were initially taken into custody by agents from the El Paso and Rio Grande Valley sectors of the Border Patrol. Before December, no child had died in Border Patrol custody in a decade.