Dec. 28 (UPI) -- Homeland Security chief Kirstjen Nielsen traveled to the U.S.-Mexico border Friday, just three days after another migrant child died there in U.S. custody.
Nasal and lung swabs taken from the body of 8-year-old Felipe Gomez Alonzo tested positive for influenza B, the New Mexico Office of the Medical Investigator said in a statement Thursday.
"While this result indicates that the child had influenza, determining an accurate cause of death requires further evaluation of other laboratory specimens and interpreting the findings in the context of the symptoms and autopsy findings," the office said.
Alonzo died early Tuesday after being hospitalized and released with a temperature earlier in the day. The child later died after returning the hospital.
Nielsen called the boy's death a "deeply concerning and heartbreaking" tragedy.
Alonzo was the second Guatemalan child to die in CBP custody this month after Jakelin Caal, a 7-year-old girl, died Dec. 8. Both attempted to migrate to the United States with their families. U.S. agents say Caal had little to eat or drink before arriving at the border, a claim the father denies.
The children's deaths prompted Sen. Dianne Feinstein, D-Calif., to call for a hearing on the treatment of children in border patrol custody, saying the Border Patrol facilities aren't equipped to care for them.
"It appears that Felipe was released from the hospital with a fever of 103, and no EMT was on duty to help him," Feinstein wrote. "Finally, I am troubled to hear about the murders of two unaccompanied children in Tijuana, who were part of the caravan The CBP is not allowing unaccompanied children into the United States at the San Ysidro port-of-entry ... The result is that these children are not able to access the asylum process at all, and they are at a high risk of falling victim to violence and exploitation in Mexico."
CBP announced Wednesday all migrant children under the age of 10 detained at the border will be medically evaluated.