Lawrence Phillips, a former NFL player convicted of inflicting great bodily injury in a domestic violence case and later charged with murdering a cellmate, was found dead in his California prison cell early on Wednesday of a suspected suicide, officials said.

The 40-year-old Phillips’ death comes less than five months after he was charged with murder in the April 11, 2015, strangling of his cellmate, a prison spokeswoman said.

He was awaiting trial in the case in Kern County, where he was held in prison in the town of Delano, about 130 miles (209 km) north of Los Angeles.

Phillips was found unresponsive shortly after midnight at Kern Valley State Prison and rushed to a hospital where he was pronounced dead early on Wednesday, the California Department of Corrections and Rehabilitation said in a statement.

The former running back, who had been kept in a prison cell by himself since the 2013 death of his 37-year-old cellmate Damion Soward, was sent to prison in 2008 to serve a sentence of more than 31 years, officials said.

He was convicted that year in San Diego County of inflicting great bodily injury in a domestic violence incident, corporal injury to a spouse, false imprisonment and vehicle theft.

Phillips played for three National Football League teams in the 1990s, finishing his four seasons in the league with the San Francisco 49ers in 1999. He later ended his playing career with stints in the Arena Football League and the Canadian Football League.

Representatives from the National Football League Players Association could not immediately be reached for comment.