U.S. Customs and Border Protection ordered new medical testing on all children in its custody, following the death of a 8-year-old Guatemalan youth caught crossing the border near El Paso, Texas, the agency said in a statement. He was taken with his father to a hospital where he was diagnosed with a common cold and given Tylenol (paracetamol).
The agency says that the boy was returned to the hospital Monday evening with nausea and vomiting.
The previous instance saw seven-year-old Jakelin Caal, also from Guatemala, die just hours after being taken into custody.
The agency said that the cause of death had not been determined, and that the Department of Homeland Security's inspector-general and the Guatemalan government had been notified.
CBP typically detains immigrants for no more than a few days when they cross the border before either releasing them or turning them over to U.S. Immigration and Customs Enforcement for longer-term detention.
Her death fuelled criticism of President Donald Trump's immigration policies from Democrats and migrant advocates, while the Trump administration said Caal's death showed the danger of her journey and the family's decision to cross the border illegally.
The CBP chief called the young boy's death "a tragic loss".
DHS wouldn't say how many children are in Border Patrol custody. CBP officers and the Border Patrol remain on the job despite the shutdown.
Now, McAleenan said CBP wants to focus on immediate care of those under the age of 10 who are brought into custody.
The Guatemalan Foreign Ministry issues a statement that it was alerted to a minor's death in the US.
In the wake of the boy's death, McAleenan announced a series of moves on Tuesday night. CBP said Felipe's father declined further medical attention because his son was feeling better.
CBP released the following timeline based on the current understanding of Felipe's final days and the hours leading up to his death late Christmas Eve.
According to a later time line issued by the agency, the boy was apprehended on December 18 at about 1 p.m. with his father 3.29 miles west of the Paso Del Norte Port of Entry near El Paso for illegal entry.
Oscar Padilla, the Guatemalan consul in Phoenix, said he was told by the boy's father in a telephone interview that the two had been travelling from their home in Nenton, a village about 450 kilometres from Guatemala City. Her body arrived in Guatemala on Monday.
A congressional oversight trip last week to the CBP station where the girl and her father were detained raised "serious concerns" about facility conditions and the "lack of adequate medical supplies, equipment and resources to properly treat migrants and the agents working there", Castro said. She was flown by helicopter to a hospital in El Paso, Texas, where she died.
Rep. -elect Xochitl Torres Small, who will represent El Paso in the House of Representatives, called for a thorough investigation into the children's deaths and medical treatment along the border.
Felipe González Morales, the United Nations special rapporteur on the human rights of migrants, said Monday that American authorities "must ensure that an in-depth, independent investigation" is conducted.