What Hartman says he didn't do is kill Snipes, who was stabbed 138 times, had her throat slit and her hands cut off. Numerous courts over the years have rejected Hartman's claim. And on Tuesday, he's scheduled to die by injection in Ohio's death chamber.
Hartman, 38, had one remaining appeal before the U.S. Supreme Court on Monday.
"Calm and cooperative" was how prisons spokeswoman JoEllen Smith described Hartman after he arrived at the Southern Ohio Correctional Facility in Lucasville on Monday morning. Hartman will be housed in a cell a few steps away from the death chamber.
Hartman presented the state with a list of 16 possible visitors, including several friends, a sister, two aunts and a niece, and he put in his order for his last meal, to be served after his visitors leave Monday.
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 Snipes' slaying and the "overwhelming evidence" of Hartman's guilt.
Hartman admitted having sex with Snipes sometime after midnight that day, going back to her apartment the following evening, finding her body and then wiping down anything he had touched, records show. He also called 911 about the body.
The county medical examiner testified that Snipes was killed late in the afternoon or early in the evening the same day, according to records.
Hartman's appeal before the U.S. Supreme Court asks that he be allowed to renew arguments that his original attorneys did a bad job presenting evidence about his troubled childhood that could have led a jury to spare him.
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.
His attorneys also 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.
In addition, they say Hartman's behavior 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 his 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.