A 52-year-old migrant from Nicaragua died in U.S. government custody, according to a Customs and Border Protection (CBP) statement. 

The man was part of a group of 36 people that surrendered to Border Patrol agents near Sasabe, Ariz. They were being processed at a Border Patrol facility in Tucson, Ariz. 

Border Patrol and emergency medical services attempted to revive the man after he fell into medical distress. He was pronounced dead at the hospital early Friday.{mosads}

CBP’s Office of Professional Responsibility is looking into the death. The Department of Homeland Security’s Office of Inspector General, the Nicaraguan government and members of Congress have also been notified. 

“Our condolences are with his family,” the statement said, adding that “CBP is committed to the health, safety and humane treatment of those in our custody.”

According to CNN, the man, who was not named, is the 12th person to die in the custody of U.S. immigration authorities since September.

Treatment of migrants in custody has faced increasing scrutiny in recent weeks following reports of poor conditions at detention facilities.