The Rev. Jesse Jackson said California's capital punishment system is flawed, and executions should be halted at the state and national levels so reforms can be devised.
Cooper had been scheduled to die at San Quentin shortly after midnight Tuesday, but the U.S. Supreme Court Monday night refused to lift a stay ordered by the lower Ninth Circuit Court of Appeals.
Jackson has been in California since last week, seeking to block Cooper's execution so new witnesses statements can be explored and physical evidence can be tested with methods unavailable after the 1983 quadruple-murder in Chino Hills.
2014: The Year in Music [PHOTOS]