OHIO, USA (AP

Ohio prepared to execute a condemned killer who claims he is innocent of stabbing a woman 138 times, slitting her throat and cutting off her hands.

Death row inmate Brett Hartman has acknowledged he had sex with Winda Snipes early on the morning of September 9, 1997 at her Akron apartment. He also says he went back to Snipes' apartment later that day, found her mutilated body and panicked, trying to clean up the mess before calling 911.

But Hartman said he didn't kill her, a claim rejected by numerous courts over the years.

The US Supreme Court denied a last-minute appeal by Hartman on Monday. He had asked the high court in his appeal that he be allowed to renew arguments that his original attorneys did a bad job presenting evidence that could have led a jury to spare him.

If executed on Tuesday, Hartman would be the 49th inmate put to death since Ohio resumed executions in 1999.

Hartman came within about a week of execution in 2009 before federal courts allowed him to pursue an innocence claim. When that claim failed, Hartman had a new date set last year, but that was postponed because of a federal lawsuit over Ohio's execution policy.

The Ohio Parole Board has unanimously denied Hartman's requests for clemency three times, citing the brutality of the Snipes' slaying and the "overwhelming evidence" of Hartman's guilt.

Hartman's attorneys have long said that crucial evidence from the crime scene and Snipes' body has never been tested, raising questions about Hartman's innocence. The evidence included fingerprints allegedly found on a clock and a mop handle. Hartman also argues the evidence could implicate an alternate suspect.

Second, the attorneys argue that if Hartman's innocence claim is not accepted, he should still be spared because of the effects of a "remarkably chaotic and nomadic early childhood," including being abandoned by his mother and left with an aunt on an isolated Indian reservation.

Third, lawyers say Hartman's behaviour in prison has been exemplary and shows he is a changed man. They cite his devotion to religious studies, his development as an artist and community service projects in prison.

The state opposes these arguments, citing the strength of the evidence and the fact that courts have repeatedly upheld Hartman's conviction and death sentence. The state also says Hartman refuses to take responsibility and show remorse.