EL PASO, Texas — Homeland Security Secretary Kirstjen Nielsen on Friday visited the Texas border city where an 8-year-old Guatemalan boy was detained with his father before dying in government custody .

DHS spokeswoman Katie Waldman said earlier in the week that Nielsen was scheduled to tour multiple stations and substations, and was also scheduled to meet with emergency medical technicians and medical professionals, as well as local officials.

Nielsen then was scheduled to go to Yuma, Arizona, on Saturday.

DHS did not release more details, saying the trip was closed to the press.

The trip came four days after the death of 8-year-old Felipe Gomez Alonzo. Felipe was the second Guatemalan child to die in government custody in three weeks.

Nielsen has called the death “deeply concerning and heartbreaking” and requested medical help from other government agencies, including the U.S. Coast Guard.

As Nielsen made the trip to Texas, New Mexico’s Democratic senators, Tom Udall and Martin Heinrich, sent her a letter Friday seeking answers about the boy’s death.

Felipe and his father, Agustin Gomez, were apprehended by border agents on Dec. 18 near the Paso del Norte bridge connecting El Paso to Juarez, Mexico, according to U.S. Customs and Border Protection.

The two were detained at the bridge’s processing center and then the Border Patrol station in El Paso, until being taken at about 1 a.m. Sunday to a facility in Alamogordo, New Mexico, about 90 miles away.

After an agent noticed Felipe coughing, father and son were taken to an Alamogordo hospital, where Felipe was diagnosed with a common cold and found to have a fever of 103 degrees, CBP has said.

Felipe was held for observation for 90 minutes, according to CBP, before being released with prescriptions for amoxicillin and ibuprofen.

But the boy fell sick hours later and was re-admitted to the hospital. He died just before midnight.