The U.S. government says a 16-year-old Guatemalan died Monday at a Border Patrol station in South Texas, the fifth death of a migrant child apprehended by border agents since December.

U.S. Customs and Border Protection said in a statement that Border Patrol apprehended the teenager in South Texas’ Rio Grande Valley on May 13. The agency says the teenager was found unresponsive Monday morning during a welfare check at the agency’s Weslaco, Texas, station. The teenager’s cause of death is unknown.

The agency did not say why the teenager had been detained for a week, but said he was “due for placement” in a facility for youth operated by the U.S. Department of Health and Human Services.

Federal law requires the Department of Homeland Security to send minors unaccompanied by a parent or legal guardian to HHS within 72 hours of determining that the child is unaccompanied.

The Border Patrol has faced months of scrutiny over its care of children it apprehends at the border. A 2-year-old child died last week after he and his mother were detained by the Border Patrol. The agency says it took the child to the hospital the same day the mother reported he was sick, and he was hospitalized for several weeks.