A 57-year-old inmate serving a life sentence at Delaware Correctional Center died Friday morning after being assaulted, the first slaying in a state prison in 10 years. Stephen F. Pytko, of Wilmington, was found unresponsive in his cell shortly after 11:30 p.m. Thursday, Delaware State Police spokesman Master Cpl. Jeffry C. Oldham said Saturday.

Pytko was pronounced dead at 12:40 a.m. after attempts to revive him were unsuccessful. His body was turned over to the state medical examiner's office, which has ruled the death a homicide but has not released a cause of death, Master Cpl. Oldham said.

Police said another inmate is a suspect, but Cpl. Oldham said he could not release the identity of the suspect or how Pytko was assaulted due to an ongoing investigation.

"We are waiting for the rest of the medical examiner's (autopsy) report and toxicology results," he said.

Cpl. Oldham said Pytko, who was housed in the medium/maximum security unit at the Smyrna prison, had a cellmate, but he would not identify him or say whether he is a suspect in the investigation. Commissioner of Corrections Stanley W. Taylor said in a release that 12 security checks of the housing unit occurred between 4 p.m. and when Pytko was found Thursday night.

"The housing unit in which Mr. Pytko was held was at full staffing levels and no one on duty was serving an overtime shift," Mr. Taylor said.

The Department of Correction has come under fire in recent years for staffing shortages and requiring correction officers to work overtime shifts, which came to light after a serial rapist took a prison counselor hostage at DCC in July 2004.

Reached by telephone Saturday afternoon, Mr. Taylor said DOC is "looking at (the situation) at our end and assisting the state police in their investigation."

Mr. Taylor would not comment further, citing the investigation. Pytko was serving a life sentence imposed in November 2003 for violating parole. The homicide comes almost exactly 10 years after the last killing inside a Delaware prison. Inmate Robert E. Ashley tabbed inmate Thomas B. Younger to death at DCC on April 28, 1996.