SAN QUENTIN (CBS SF) — Condemned Inmate John Abel, sentenced to San Quentin’s death row after evidence linked him to a 1992 Orange County slaying, has died at a local hospital, prison officials announced Saturday.

Officials said Abel had been taken to a hospital outside the prison were he was pronounced death on Saturday morning. His cause of death was unknown pending the results of an autopsy, but foul play was not suspected.

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Abel had been in prison since 1992 when he was admitted from Los Angeles County to serve 44 years and eight months for a string of armed robberies. He was also serving a seven-year sentence for second-degree robbery with the use of a firearm.

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But in 1997, while incarcerated, Abel was charged in the 1991 killing of Armando Miller, who was shot at point-blank range at a Tustin bank and robbed of $20,000 that had just been withdrawn from the bank.

An anonymous tip led Tustin police to Abel and during the trial evidence was presented that he had bragged to a girlfriend that he killed Miller. He twiddled his thumbs and grinned as Judge Robert Fitzgerald as he was sentenced to death, according to the Orange County Register.

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Since 1978, when California reinstated capital punishment, 82 condemned inmates have died from natural causes, 27 have committed suicide, 13 were executed in California, one was executed in Missouri, one was executed in Virginia. Another 14 have died from other causes and seven – including Abel – are pending a cause of death. There are 728 people on California’s death row.