J.C.X . Simon , 69 , and three other men participated in the racially-motivated attacks in the 1970s . A 69-year-old black man who was convicted of participating in the infamous 'zebra murders ' in San Francisco , California , in the 1970s was found dead at San Quentin State Prison . J.C.X . Simon was one of four black men convicted of carrying out a string of racially-motivated attacks that killed 14 people and injured seven . He was found in his one-man cell shortly before midnight Thursday , according to the California Department of Corrections and Rehabilitation . The cause of death is unknown and an autopsy is planned . Simon was convicted of two first-degree murder charges , conspiracy to commit first-degree murder and assault with a deadly weapon in 1976 and was serving a life sentence with the possibility of parole , the maximum sentence allowed In California at the time . The killing spree was dubbed the 'zebra murders ' because of the special Z channel radio band investigators used , the San Francisco Gate reported . During a six-month murder spree from October 1973 to April 1974. the four men targeted white victims and murdered the majority of them with an execution-style shot to the back of the head . The other three men who were convicted - Larry Green , Manuel Moore and Jessie Lee Cooks - are serving life sentences at other California prisons . The trial saw 174 witnesses testify and was described as 'San Francisco 's longest criminal trial ' at the time . The victims were aged 15 to 87 and did not know one another , the Los Angeles Times reported . Simon was convicted of two first-degree murder charges , conspiracy to commit first-degree murder and assault with a deadly weapon in 1976 . He was sentenced to life with the possibility of parole . In addition to Simon , Larry Green ( left ) , Manuel Moore ( center ) and Jessie Lee Cooks ( right ) are also serving life sentences with the possibility of parole . In order to stop the murders , then-Mayor Joe Alioto ( pictured announcing the arrests ) ordered a city-wide dragnet in San Francisco , Caliornia , to catch the killers . In order to stop the murders , then-Mayor Joe Alioto ordered a city-wide dragnet to catch the killers . Police stopped and questioned nearly every young black man they encountered between the ages of 20 and 30 who were 6ft tall or a few inches shorter . Those questioned and cleared were given a card to show other officers who detained them . A federal judge eventually put a stop to the practice . After getting a tip from an informant , police raided an apartment complex and arrested seven men . Simon , Cooks , Green and Moore were the only ones who were charged . The victims who were wounded were instrumental in helping police come up with composite sketches ( above )
J.C.X . Simon participated in the racially-motivated slayings in the 1970s . Simon and three other black men were convicted of targeting white people . Six-month crime spree from October 1973 to 1976 also injured seven . Convicted in April 1974 and was serving life sentence with possibility of parole .