Kennedy cousin Michael Skakel lost his bid for a new trial in the 1975 slaying of his 15-year-old neighbor when the state Supreme Court on Monday rejected his appeal that cited a claim implicating two other men.

The court ruled 4-1 against Skakel's request, saying the evidence doesn't back up the alternate claim.

Skakel — a nephew of Robert Kennedy's widow, Ethel — was sentenced to 20 years to life in prison in 2002 for fatally beating Martha Moxley with a golf club in 1975 in a wealthy Connecticut suburb. Monday's decision came after years of appeals and a campaign by Skakel's cousin, Robert Kennedy Jr.

Skakel, 49, had asked for a new trial after Gitano "Tony" Bryant, who attended the same private school as Skakel, implicated his two friends in the killing. A judge turned that request down in 2007, and Skakel then appealed to the high court.

Bryant gave a videotaped statement to an investigator hired by Skakel in which he said his two friends were in Greenwich the night Moxley was killed. He said they told him they got Moxley "caveman style."