click to enlarge Marcellus Williams

Over objections by civil rights groups contending that evidence points to a different perpetrator, convicted murderer Marcellus Williams is scheduled to die tomorrow at 6 p.m. by lethal injection. It would be second execution carried out under Missouri Governor Eric Greitens. Barring intervention by the U.S. Supreme Court, Greitens is now the only person who can spare Williams' life.Williams' case has drawn recent attention — and a change.org petition with more than 150,000 supporters — over what his lawyers say is crucial DNA evidence discovered on the knife used in the 1998 slaying of Lisha Gayle, a formerreporter.Although the case against against Williams lacked forensic evidence, the testimony of Williams' girlfriend and a former cellmate were enough to convince a jury of his guilt. Williams was convicted in 2001 and sentenced to death.However, Williams' lawyers argue that the witnesses were actually angling for the $10,000 reward offered by Gayle's family in return for information leading to the murderer. Last week, they asked the Missouri Supreme Court to halt the execution, saying that DNA evidence on the knife points to an unknown man, not Williams.But the state's highest court said no "We petitioned the court to look at the new evidence on August 14, and less than 24 hours later they decided based on the court files that the execution should go ahead anyway. This is unprecedented," Williams' attorney, Kent Gipson, told Al-Jazeera In aop-ed published Sunday , ACLU-Missouri Executive Director Jeffrey Mittman implored the governor to stop the execution. The existence of the DNA evidence, he wrote, casts "more than enough to justify a new trial or, at a minimum, a commutation of his sentence."