San Diego County Medical Examiner's Office at the County Operations Center.
San Diego County Medical Examiner’s Office at the County Operations Center. Photo by Ken Stone

An inmate found unresponsive at San Diego Central Jail died of natural causes, authorities said Thursday.

The San Diego County Sheriff’s Department described the finding in Thursday’s autopsy as the “preliminary manner of death.” When the complete autopsy report is received, the man’s specific cause of death will be revealed, officials said.

Deputies doing security checks on the seventh floor of the jail found the inmate, 64, shortly after midnight Wednesday. Medics pronounced him dead just before 1 a.m.

The department continued to withhold the man’s name as officials attempt to find his family members.