A 16-year-old from Guatemala is the latest minor to die in U.S. Customs and Border Protection (CBP) custody, CBP announced on Monday, May 20. According to the agency, which oversees the Border Patrol, the teenager was apprehended by Border Patrol agents on May 13 and processed near Hidalgo, Texas, before he was sent on Sunday to a Border Patrol station near Texas’s southern tip.

CBP wrote that the teen was found unresponsive during a welfare check on Monday. The agency said it would not reveal his identity, that his cause of death is currently unknown, and that CBP’s Office of Professional Responsibility has initiated a review.

“The men and women of U.S. Customs and Border Protection are saddened by the tragic loss of this young man and our condolences are with his family,” said CBP acting commissioner John Sanders in a statement. “CBP is committed to the health, safety, and humane treatment of those in our custody.”

As noted by NBC News, the teen is the fifth migrant child to die in U.S. custody since December, all five of whom were from Guatemala: Jakelin Caal Maquín, age 7, died of a bacterial infection in CBP custody in December; Felipe Gomez Alonzo, 8, may have had the flu when he died in CBP custody on Christmas Eve; Juan de León Gutiérrez, 16, died on April 30 in Department of Health and Human Services custody, after he left his Guatemala home due to the agricultural impacts of climate change, Time reported. And on May 14, an unidentified toddler, age two and a half, died in CBP custody after several weeks in the hospital, according to The Washington Post.

According to CBP data, Guatemalans are the national group with the largest numbers of family-unit unaccompanied-children border apprehensions. While gang violence has long been seen as a reason for Guatemalan migrants to emigrate, CBP said in September that it believes a major drought and fungus infecting the country’s coffee crops are fueling the migration of indigenous families from the country’s western regions. Multiple reports in recent months have linked that drought to climate change.

In a statement regarding this most recent death, human rights group Amnesty International was critical of the condition in which the U.S. detains migrants.

“It is dangerous and cruel to detain people, particularly children, in crowded and unsanitary conditions for seeking protection,” Amnesty International tactical campaigns manager Ashley Houghton said in the statement. “The administration must respect human rights by ending detention of children.”

Human rights groups like Human Rights Watch have also been critical of detention conditions, especially the use of “hieleras” (or “iceboxes”), a name used by detainees that refers to how cold the facilities are often kept.

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