A 56-year-old sex offender was found dead early Sunday morning in his cell at the Sacramento County Mail Jail.

Sacramento sheriff’s spokeswoman Sgt. Lisa Bowman said the inmate, who was being held on a sexual registration violation charge, was discovered unresponsive in his cell shortly after 3:30 a.m. Authorities said the death does not appear to be suspicious.

The Sacramento County Coroner’s Office is investigating the cause of death. The inmate’s name was being withheld, pending notification of family members, Bowman said.