NEW HAVEN, Conn. – Michael Skakel plans to call his cousin Robert F. Kennedy Jr. and his celebrity trial attorney as witnesses for an appeal of his murder conviction that starts next week on a claim that two other men may have committed the crime.

Skakel, a nephew of Ethel Kennedy, is seeking a new trial based on a claim by Gitano “Tony” Bryant, who implicated his friends in the killing of 15-year-old Martha Moxley. Skakel, 47, was convicted in 2002 of bludgeoning Moxley to death with a golf club in 1975 in Greenwich and is serving 20 years to life in prison.

Bryant made the claim in 2003 in a videotaped interview with Skakel’s private investigator, Vito Colucci Jr. But Bryant and the two men he implicated have invoked their Fifth Amendment right against self-incrimination.

Bryant said he was with two friends from New York in Greenwich the night Moxley was killed. According to court papers, Bryant said one friend had met Moxley and “wanted to go caveman on her,” and that after he left them that night, they later told him, “We did what we had to do.”

Benedict called Bryant’s account “a complete fabrication.” Hope Seeley, Skakel’s attorney, who filed a revised witness list Tuesday, said a jury should hear the claim.

The wife of one of the men Bryant implicated has called the claim a lie, while the other man has not returned telephone calls.

Prosecutors say in court papers that they plan to call Skakel, his sister and numerous other witnesses to refute Bryant’s claim that he was in the Greenwich neighborhood the night Moxley was killed. Skakel is expected to exercise his Fifth Amendment right not to testify if called.

Prosecutors also plan to call John Moxley, the victim’s brother, to identify her diary and refute Bryant’s claim that he knew Moxley, according to court papers.

A hearing on Skakel’s petition for a new trial is scheduled to start Tuesday in Stamford Superior Court. To win a new trial, Skakel’s defense must show that Bryant’s account is evidence discovered after the conviction and that it likely would have changed the verdict.

Robert F. Kennedy Jr. put Skakel’s attorneys in touch with Bryant after learning of the claim from a man who attended a private school with Bryant and Skakel. Kennedy said in 2003 that both of Bryant’s friends told him they knew Moxley and acknowledged being in Greenwich in the past.

A witness from the state forensic lab is expected to testify that “a dark brown to black head hair possessing negroid characteristics” was found on the sheet used to wrap the victim’s body, according to court papers. Bryant and one of the men he implicated are black.

Forensic experts testified about the hair at Skakel’s trial. It’s unclear whose hair it was.

Another defense witness described as Bryant’s “surrogate mother” while he attended private school in Greenwich will testify that Bryant told her he was in the neighborhood the night Moxley was murdered and that he knew Skakel was not guilty, according to court papers.

Skakel’s trial attorney, Michael Sherman, is on the witness list for both sides. Sherman, who frequently appears on television shows about high-profile trials, will testify whether he knew about Bryant’s claim before the trial.

Skakel plans to call Bryant’s mother and witnesses expected to contradict what Bryant’s mother says in her deposition regarding his whereabouts.

Skakel’s appeal also challenges the testimony of Gregory Coleman, who said Skakel confessed to him when they attended a reform school in Poland, Maine, in the late 1970s. Coleman later died of a drug overdose.

Skakel’s attorneys plan to call witnesses who do not corroborate Coleman’s claim that another resident of the school witnessed the admission. Prosecutors declined to comment.

In November, the U.S. Supreme Court decided not to take up Skakel’s appeal, which claimed a statute of limitations had expired before he was charged.