An investigation is underway after a man died in custody at a Contra Costa detention facility on Sunday, authorities said. 

The Contra Costa County Sheriff's Office said a deputy found an inmate responsive in his cell at the Martinez Detention Facility just after 5 p.m.

Medical staff responded, as well as firefighters and an ambulance, but the inmate died at the scene, authorities said.

The inmate was identified as 62-year-old Victor Jose Faria, a man who deputies say was homeless and arrested on Thursday for trespassing and felony probation. 

The Contra Costa Sheriff's Office and Contra Costa District Attorney's Office will investigate the death.