With his tall Stetson hat, diamond rings, gold chains and a thin handlebar mustache, attorney Johnny Mostiler was for years the face of indigent defense at the Spalding County courthouse.

Known as "Boss Hog," Mostiler drove a Cadillac convertible with cow horns as hood ornaments and, over a decade, held the contract for Spalding's public defender work. On top of a civil practice, Mostiler carried more than 600 indigent criminal cases at a time.

Mostiler died of a massive heart attack in 2000. On Friday, his defense of killer Curtis Osborne 18 years ago will be the focus of lawyers asking the Board of Pardons and Paroles to commute Osborne's death sentence.

Osborne's lawyers from the Atlanta firm King & Spalding contend Mostiler was so racially prejudiced he presented a paltry defense on his client's behalf. They will allege that Mostiler, who was white, did not tell Osborne, who is African-American, there was an offer for Osborne to plead guilty to a life sentence.

"The system breaks down when it's infected or corrupted by racism," said Bill Hoffmann, one of Osborne's lawyers. "It's a fundamental principle of our justice system that individuals be given zealous representation. It's particularly outrageous that Mr. Osborne was denied that because of racial bias."

In 2006, the federal appeals court in Atlanta rejected claims that Mostiler's alleged racial animosity entitled Osborne to a new trial. The court noted that Mostiler, called to testify during Osborne's appeal, said he recalled giving Osborne the state's offer to plead to life in prison.

Osborne is scheduled to be executed by lethal injection on June 4. He was sentenced to death for fatally shooting Linda Lisa Seaborne and Arthur Jones on Aug. 7, 1990.

Prosecutors said Osborne killed Jones after selling Jones' motorcycle and not giving him the money back and then shot Seaborne to eliminate her as a witness.

The parole board will hear the clemency request eight days after it spared Samuel David Crowe hours before he was to be executed.

Former President Jimmy Carter, former deputy U.S. Attorney General Larry Thompson and former Georgia Supreme Court Chief Justice Norman Fletcher are sending letters to the board, requesting clemency for Osborne, Hoffmann said.

Fletcher, who voted in 1993 to uphold Osborne's death sentence, said he recalled Mostiler's "apparent ineptness" because he raised so few issues on appeal.

"As is now all too well apparent, it is Mr. Osborne who is suffering due to Mr. Mostiler's grave shortcomings and his racial prejudices of perhaps a lifetime," Fletcher wrote the board.

Spalding County District Attorney Scott Ballard wants the execution to go forward.

"It's been 18 years since a jury, after hearing all the evidence and, I believe, being presented with a very adequate defense by Mr. Mostiler, sentenced him to death," Ballard said. "This case has been reviewed and reviewed and reviewed. It's time to carry it out."

Long-time Griffin attorney Andrew Whalen III called Mostiler a compassionate defender of all his clients, regardless of their race.

"I felt like he really gave it his all," he said. "He enjoyed a good trial and a good fight in the courtroom."

As to whether Mostiler was racially biased, Whalen said, "The whole thing sounds absurd to me. I certainly would not contend he was racist at all."

Osborne's lawyers will provide the board with evidence from two former Mostiler clients who said they heard him use racial slurs.

One of them, Gerald Steven Huey, said Mostiler once said of Osborne, "That little [racial epithet] deserves the death penalty."

Both Huey, convicted in 1991 of murdering and dismembering his drinking buddy, and Osborne were in the Spalding County jail as they awaited their trials.

Huey said that Mostiler once told him he was going to spend a lot of money defending Huey. "He said the money he would spend on me was going to be a lot more than he would spend on Mr. Osborne because 'that little [racial epithet] deserves the chair,'" Huey said.

On another occasion, Huey said, Mostiler came to him with an offer from the district attorney to plead guilty in exchange for a life sentence. But Huey declined.

"Mr. Mostiler got furious and told me how lucky I was," Huey said. "He said that he had an offer for Curtis Osborne but he would never tell Mr. Osborne about it because he deserved to die."

Huey, dumbfounded, said he asked Mostiler if he was on a crusade, according to his affidavit, signed in April 2001. "He said that he believed that some people deserved to walk and some didn't, and if that was a crusade then he was on one," Huey said.

In 2000, Derrick Middlebrooks, an African-American client of Mostiler's, later convicted of drug offenses, told Superior Court Judge Johnnie Caldwell he lost confidence in Mostiler when he heard the lawyer use a racial epithet.

Mostiller didn't deny using the term. "I honestly can't say whether I said it or not, I don't — I honestly don't remember," Mostiler said, when asked by Caldwell about it, according to a transcript of the hearing.

"Derrick's used those terms and I've used those terms with him," he said. "I don't use those terms out in public....If I did use it I certainly am sorry."

Before Osborne's trial, Mostiler did not request funds for a mental health expert or for a mitigation expert to investigate his client's life.

Psychiatrist George Woods, an adjunct professor at the Morehouse School of Medicine, said if experts had been hired, they would have learned Osborne's family had a history of mental illness.

Osborne, who for years held a steady job at a furniture store, spiralled out of control before the murders when he became both addicted to cocaine and mentally ill, said Woods, hired by Osborne's legal team.

"His family history was so strong, both in terms of chemical dependency and mental illness," Woods said. "It would have been powerful for the jury to know that the mental illness he developed didn't just happen the day before the offense."

This is not the only time Mostiler's failure to investigate the background of a client in a death-penalty case has been attacked on appeal.

Frederick Whatley sits on death row for a 1995 armed-robbery murder. At his trial, Mostiler told jurors if Whatley had stayed with his family in Griffin, "where he had been taught right, where he had been raised correctly, I don't think we would have been here today."

New lawyers for Whatley later investigated his background. In court filings, they say Whatley, until he was 16, slept in the same bed with his uncle who molested him repeatedly.