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HUNTSVILLE (AP) — The U.S. Supreme Court is considering multiple appeals from lawyers trying to keep a Texas inmate from execution Wednesday evening for a slaying 15 years ago that the man claims was accidental.

Richard Masterson, 43, would be the first inmate put to death this year in the nation’s busiest death penalty state, where 13 lethal injections in 2015 accounted for nearly half of the 28 executions nationwide.

Masterson was sentenced to death for the January 2001 strangulation of Darin Shane Honeycutt, 35, a female impersonator he’d met at a bar. He testified at his Houston trial that Honeycutt’s death was the result of an accidental asphyxiation during sex and not an intentional murder.

Evidence showed Masterson stole Honeycutt’s car, dumped it in Georgia, and was arrested at a Florida mobile home park more than a week later with another stolen car. That car belonged to a Tampa, Florida, man who testified that he was robbed by Masterson but survived a similar sex episode where he was choked.

At least four appeals on Masterson’s behalf were before the Supreme Court.

His attorneys are arguing that Honeycutt’s death was accidental or the result of a heart attack, that a Harris County medical examiner whose credentials have been questioned was wrong to tell jurors it was a strangulation, that Masterson’s earlier lawyers were deficient for failing to discover that information and that his prolonged drug use and then withdrawal while in jail contributed to his “suicide by confession” when he spoke to police about the slaying.

“Mr. Masterson’s case presents a perfect storm of attorney incompetence and neglect combined with a severely mentally ill, suicidal defendant who did not kill anyone,” attorney Gregory Gardner said in a filing to the high court.

Lawyers also contend that the Texas Court of Criminal Appeals denied Masterson his rights to due process and access to the courts by refusing their challenge to a new state law that keeps secret the identity of the provider of pentobarbital that Texas prison officials use for lethal injections.

State lawyers argued that Masterson’s attorneys offered no scientific evidence about Honeycutt’s death that hadn’t been previously raised and rejected, including by jurors at Masterson’s trial.

“He is simply attempting to present identical facts under a different legal theory and using different experts in order to pass off the allegation as ‘new,'” Erich Dryden, an Texas assistant attorney general, told the justices.

According to court filings, besides confessing to police, Masterson told a brother he killed Honeycutt and wrote to Texas’ then-Attorney General Greg Abbott in 2012 acknowledging the slaying.

“I meant to kill him,” Masterson wrote to Abbott, who is now Texas’ governor. “It was no accident.”

Masterson had a long drug history and criminal record beginning at age 15. Court documents showed he ignored advice from lawyers at his 2002 trial and insisted on telling jurors he met Honeycutt, who used the stage name Brandi Houston, at a bar and they went to Honeycutt’s Houston apartment where Masterson said the chokehold was part of an autoerotic sex act.

Honeycutt’s body was found Jan. 27, 2001, after friends became worried when he failed to show up for work.

Masterson also told jurors he was a future danger — an element they had to agree with in order to decide a death sentence was appropriate.

Masterson’s case has recently drawn the attention of Pope Francis, who has reinforced the Catholic Church’s opposition to capital punishment.

At least eight other Texas death row inmates have executions scheduled for the coming months, including one set for next week.

(© Copyright 2016 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)