An autopsy will be conducted on a 35-year-old Butler County man who died Tuesday — a day after he was found unresponsive in his state prison cell in Fayette County, authorities said.

Raymond M. Seybert, a convicted violent sex offender, was unconscious about 10:20 a.m. Monday when staff at the State Correctional Institution- Fayette found him during a routine security check.

Prison officials reportedly provided emergency first aid before Seybert was taken to Uniontown Hospital.

He eventually was transferred to UPMC Presbyterian in Pittsburgh, where he was pronounced dead at 5:36 a.m. Tuesday, according to the Allegheny County Medical Examiner’s Office.

An autopsy is planned today or Thursday to determine a cause of death, authorities said.

State police are investigating the case. No other details were available this morning.

Seybert had been at SCI-Fayette since June 2004 while serving a 10- to 32-year sentence for sexually assaulting a 14-year-old Penn Township girl.

A Butler County jury convicted him in the 2001 assault.