Deputies are investigating the death of a 53-year-old inmate at the Ventura County jail Saturday night, officials said Sunday.
Deputies noticed a Simi Valley woman was not breathing during routine cell checks about 10:20 p.m. at the Pre-Trial Detention Facility, authorities said.
After entering the cell, deputies administered emergency aid to the woman, officials said.
The Ventura County Fire Department responded to reports of a seizure at the jail about 10:25 p.m., fire officials said.
Emergency responders performed advanced lifesaving support, but Eydie Stepelton was pronounced dead at 10:43 p.m., authorities said.
There was no indication of violence or suspicious circumstances, and the death appears to be from natural causes, deputies said.
The sheriff's major crimes unit is investigating the incident, officials said.
"In custody deaths we do a thorough investigation" to rule out any possible inappropriate behavior, Capt. Bill Flannigan said.
An autopsy was completed Sunday afternoon. Stepelton's cause and manner of death are pending toxicology, histology and electrolyte studies, according to the Ventura County Medical Examiner's Office.
A bench warrant was issued for Stepelton on July 23 after she failed to appear in court for a domestic violence case, court records show.
Simi Valley police arrested Stepelton on Friday, records show.