Kennedy is expected to be a witness Tuesday in a Superior Court hearing that will be Skakel's latest bid to overturn his 2002 conviction.
Skakel, a nephew of Ethel Kennedy, is serving 20 years to life in prison after he was convicted of bludgeoning Martha Moxley to death with a golf club in their wealthy Greenwich neighborhood when they were 15.
Skakel's attorneys plan to present a claim by one-time schoolmate Gitano "Tony" Bryant that implicates two of his friends in Moxley's death. Kennedy was involved in bringing Bryant's claim to the attention of Skakel's attorneys.
Prosecutor Jonathan Benedict has called Bryant's account "a complete fabrication."
Skakel's attorneys say a jury should hear the allegation.
To win a new trial, Skakel's defense must show that Bryant's account is evidence not available at the time of his trial and that it likely would have changed the verdict. Moxley's mother has said she still believes Skakel is guilty.
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 the two later told him "We did what we had to do" and "We got her caveman style."
Kennedy 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.
Bryant's claim surfaced in 2003 when he gave a videotaped interview to Skakel's private investigator, Vito Colucci Jr. But since then, Bryant and the two men he implicated have invoked their Fifth Amendment right against self-incrimination.
The wife of one of the men Bryant implicated has called the claim a lie, while the other man has not returned telephone calls.
The non-jury hearing could last as long as two weeks.
Esme Dick, described as Bryant's "surrogate mother" while he attended private school in Greenwich, will testify for the defense that Bryant told her he was in the neighborhood the night Moxley was killed and that he knew Skakel was not guilty, according to court papers.
Prosecutors say in court papers 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.
Skakel's trial attorney, Michael Sherman, is on the witness list for both sides. He will testify about whether he knew of Bryant's claim before the trial.
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.