Prison officials are investigating the death of a condemned inmate found in his cell, a San Quentin Prison spokesman said.
There was no sign that Marcelino Ramos' death Monday was due to foul play or drugs, Eric Messick said.
Ramos, 49, was one of two people convicted in the 1979 execution-style slaying of a Taco Bell worker in Santa Ana. Ramos was the janitor at the restaurant when he and co-defendant Rueben Gaitan robbed the store.
Katharyn Parrott, 20, was killed; the other worker survived.