San Quentin, Calif. ? Gov. Arnold Schwarzenegger refused to block the execution of Stanley Tookie Williams, rejecting the notion that the founder of the murderous Crips gang had atoned for his crimes and found redemption on death row.

With the U.S. Supreme Court rejecting his final appeal, Williams, 51, was set to die by injection at San Quentin Prison early today for murdering four people during two 1979 holdups.

Williams’ case became one of the nation’s biggest death-row cause celebres in decades. It set off a nationwide debate over the possibility of redemption on death row, with Hollywood stars and capital punishment foes arguing that Williams had made amends by writing children’s books about the dangers of gangs.

But Schwarzenegger suggested Monday that Williams’ supposed change of heart was not genuine, noting that the inmate had not owned up to his crimes or shown any real remorse for the countless killings committed by the Crips.

Williams’ supporters were disappointed with the governor’s refusal to commute the death sentence to life in prison without parole.

Williams stood to become the 12th person executed in California since lawmakers reinstated the death penalty in 1977.

He was condemned in 1981 for gunning down convenience store clerk Albert Owens, 26, at a 7-Eleven in Whittier and killing Yen-I Yang, 76, Tsai-Shai Chen Yang, 63, and the couple’s daughter Yu-Chin Yang Lin, 43, at the Los Angeles motel they owned. Williams claimed he was innocent.

Torre Brandon Reese, a junior high school teacher, joins others as they react to the news of Calif. Gov. Arnold Schwarzenegger's denial of clemency to Stanley Tookie Williams on Monday in the Leimert Park area of Los Angeles. Williams was scheduled to die at 12:01 a.m. (2:01 CST) today.

Just before the governor announced his decision, the 9th U.S. Circuit Court of Appeals denied Williams’ request for a reprieve, saying there was no “clear and convincing evidence of actual innocence.”

Later in the evening, additional last-ditch requests to halt the execution were rejected by the U.S. Supreme Court, the 9th Circuit and Schwarzenegger. Just three hours before Williams was scheduled to die, his lawyers sent the governor another request for a stay, saying a fourth witness who could help prove his innocence had come forward. It was uncertain whether Schwarzenegger would respond.

Williams and a friend founded the Crips in Los Angeles in 1971. Authorities say it is responsible for hundreds of deaths, many of them in battles with the rival Bloods for turf and control of the drug trade.