The death of a condemned inmate on San Quentin's death row is being investigated as a possible suicide, prison officials said Tuesday.
Michael Lamont Jones, 44, was pronounced dead Monday afternoon at 3:51 p.m.
An official determination of the cause of death has not been made, pending an autopsy, but officials said the death is considered a possible suicide.
Jones was sentenced to death on Dec. 13, 1991 for the Jan. 21, 1989 murder of Herman Weeks, 24, in Riverside County. Weeks was killed during an armed robbery at a Domino's Pizza store.
Prison officials said 66 condemned inmates have died of natural causes on death row since 1978, when California resumed use of the death penalty. Another 24 have committed suicide, seven have died from other causes, and the causes of death for four are still pending. Only 13 have been executed in California during that time, and one in Missouri.