SAN QUENTIN (CBS SF) — A 67-year-old death row inmate died of unknown causes at San Quentin State Prison in Marin County on Wednesday evening, according to the California Department of Corrections and Rehabilitation.

Raymond Edward Steele was found unresponsive in his cell and was pronounced dead at 7:37 p.m. Wednesday. The cause of Steele’s death is pending an autopsy, according to CDCR officials.

Steele was sentenced to death in 1990 for fatally stabbing a mentally handicapped woman in Shasta County in 1988. He had a prior conviction for rape in 1971 as well as for the second-degree murder of his 15-year-old babysitter, CDCR officials said.

Steele had been on death row since July 31, 1990, nearly 25 years.

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