Barring a reprieve from the U.S. Supreme Court or clemency from the governor, Dale Leo Bishop will be executed Wednesday for participating in the claw hammer beating death of one of his friends.

The execution is scheduled for 6 p.m. at the Mississippi State Penitentiary at Parchman.

Bishop’s attorneys say his life should be spared because he did not swing the hammer that killed Marcus James Gentry in 1998. Bishop also claims his bipolar disorder prevented him from making a sound decision when he asked for the death penalty in 2000.

Bishop acknowledges participating in the attack, but another man, Jessie Johnson, admitted striking the lethal blows. Johnson was tried separately and sentenced to life without parole.

It’s not clear if that will persuade Gov. Haley Barbour to spare Bishop’s life. Barbour has not granted clemency to any of the three inmates executed since he took office in 2004.

If Barbour doesn’t grant clemency, Bishop’s last hope appears to the be the U.S. Supreme Court. The 5th U.S. Circuit Court of Appeals in New Orleans on Tuesday rejected a request that Bishop be allowed to argue in an appeal that one of his former lawyers suppressed evidence of his bipolar disorder and intentionally sabotaged his case. The 5th Circuit said that issue had been denied once and Bishop could not argue it again.

Jim Craig, Bishop’s current attorney, said he would appeal the 5th Circuit ruling to the U.S. Supreme Court. That would bring to three the number of Bishop’s appeals pending before the nation’s highest court. One of those is based on a lawsuit filed on behalf of Bishop and other death row inmates in 2007 to stop all executions in Mississippi. The inmates claimed the procedure is unconstitutional because it could cause pain.

The state attorney general’s office has declined to discuss the specifics of the case.

“Mr. Bishop still has appeals waiting to be heard. We are answering those appeals in court and will await those decisions with the expectation that his sentence will be carried out on Wednesday,” said Jan Schaefer, a spokeswoman for Attorney General Jim Hood.

Lee County Sheriff Jim H. Johnson, who worked as an investigator at the time of Gentry’s murder, called the crime “the worst case of disregard for human life” that he’s ever seen.

“Mr. Bishop’s acts alone may not have caused the death, but he was certainly a main player in the death of Mr. Gentry. There’s no question in my mind about it,” the sheriff said. “And that was not only my opinion, that was the opinion of 12 jurors.”

The attack began in Gentry’s car after a night of drinking and drug use and continued on a dirt road near Saltillo in north Mississippi, according to court records. Bishop held Gentry while Jessie Johnson hit the 22-year-old victim with the hammer.

“Mr. Gentry was able to jump up and flee the scene. Dale Bishop, under his own admission, chased him down by himself, drug him back in front of the headlights because it was dark at night, and then they began delivering blows again to the head with this hammer,” Sheriff Johnson said.

The sheriff said Bishop also admitted using the guise of working on his truck to bring the hammer along that night.

A federal district judge said the statute of limitations had passed and dismissed the lawsuit last week. Bishop’s attorneys appealed the dismissal to the 5th Circuit, saying the Mississippi Department of Corrections withheld information about the procedure and stalled until time ran out.

Instead of ruling on whether a statute of limitations would apply when one party is accused of withholding information, a panel of 5th Circuit judges ruled on the underlying issue. The split panel ruled Monday in a 2-1 decision that Mississippi’s method of lethal injection is constitutional.

Bishop’s attorneys challenged that decision with the U.S. Supreme Court.

“If Bishop and the remaining plaintiffs are not allowed to litigate their claims — or even have discovery on the development and imposition of the protocol at issue — then the question of whether Mississippi’s protocol passes constitutional muster may never be answered,” the petition said.

The other petition before the court requests a definitive ruling on whether statute of limitations apply in a case in which one party is accused of withholding information.

Bishop would be the second man executed in Mississippi this year.