SAN DIEGO–Sheriff’s deputies doing a security check at the George Bailey Detention Facility found an inmate unresponsive in his cell.

Deputies performed first aid until paramedics arrived, but despite lifesaving efforts, the man died. The deceased man was alone in his secure cell and no preliminary evidence of injury or foul play was discovered.

The man was in custody for charges including convictions for assault of police officer or firefighter with a deadly weapon, inflicting great bodily injury, and felony resisting an officer, according to San Diego Sheriff’s Department spokesman, Lt. Rich Williams.

The Sheriff’s homicide detectives are investigating his death.

The San Diego County Medical Examiner’s Office will conduct an autopsy to determine the cause and manner of death, and notify the family.