US authorities have now acknowledged the death of a 10-year-old girl from El Salvador after she was detained by American border agents eight months ago.
It takes the death toll of migrant children in US custody in 2018 to six.
The child, who had a history of congenital heart defects and died in September, was the first migrant minor to die in US custody in last year, but her death was not reported by authorities until Wednesday.
It comes days after a 16-year-old Guatemalan boy died after being detained for a week by Border Patrol agents in Texas.