An inmate at the Bexar County Jail was found unconscious and later pronounced dead Saturday night.
Jail officials say a guard on the sixth floor of the Adult Detention Center found 32-year-old Antonio Obregon bleeding on the floor and unresponsive.
Paramedics transported to San Antonio Military Medical Center where he was pronounced dead.
An investigation is underway into Obregon's death. "When people are brought to this jail, it is our duty to keep them safe, when something happens, we owe it to the citizens of Bexar County," said Paul Berry with the Bexar County Sheriff's Office.
Jail officials do not believe that any other inmates were involved in Obregon's death and it did not appear to be a suicide.
Obregon was booked on aggravated robbery charges and had been in the jail since October.