After nearly 25 years on California's death row, time could run out today for Stanley Tookie Williams. Unless Gov. Arnold Schwarzenegger grants clemency or the 9th U.S. Circuit Court of Appeals approves a petition his attorneys filed late Sunday, Williams will be executed just past midnight for the 1979 shotgun slayings of four people in Los Angeles.

Williams was still clinging to hopes of mercy Sunday as the California Supreme Court rejected another appeal and the governor continued to consider whether to spare the co-founder of the notorious Crips gang for his transformation into a death row apostle against gang violence. After the high court rejection late Sunday, Williams' lawyers filed a virtually identical petition with the San Francisco appeals court. A decision is expected today on the fate of the 51-year-old convict.

If the appeals court denies the last-ditch effort, Schwarzenegger would be the last hope for Williams, whose case has attracted international attention and thrust the death penalty debate back into the public limelight in California. Schwarzenegger has rejected the only two clemency petitions he has considered from death row inmates, including deciding against a reprieve for San Mateo killer Donald Beardslee the day before his execution in February.

Los Angeles prosecutors have argued vigorously against clemency, saying he has not apologized for his crimes and has had ample opportunity to argue his case in the courts. Victims' family members also want to see Williams executed.