A 43-year-old transient died in San Luis Obispo County Jail on Monday.

Joseph Morillo was found unconscious in a cell and pronounced dead at 4:33 p.m. after unsuccessful attempts to resuscitate him, according to Sheriff's Office spokesman Tony Cipolla.

Morillo, who was booked into County Jail on Sept. 30 by Paso Robles police on suspicion of making terrorist threats, was being held in a safety cell designed for inmates considered a danger to themselves or others, according to Cipolla. Correctional officers found Morillo while performing one of the regular checks, done twice every half-hour, of inmates in the safety cell.

When correctional staff discovered that Morillo was not breathing, they administered CPR and used an automated external defibrillator to try to revive him. Morillo had a prior medical history, Cipolla said.

The coroner will perform an autopsy to determine the cause of death.