SACRAMENTO, Calif. (AP) — California corrections officials say a 74-year-old sex offender sentenced to death for killing a woman and three of her children has died on death row.

Richard Allen Benson was found unresponsive alone in his San Quentin State Prison cell early Monday. He was pronounced dead about a half-hour later.

Officials said Tuesday that foul play is not suspected, but his cause of death will be determined by the Marin County coroner.

He was sentenced to death for four counts of first-degree murder in the 1986 slayings of Laura Camargo and three of her children in San Luis Obispo County.