The state's highest court has upheld Kennedy cousin Michael Skakel's murder conviction, according to the victim's mother, who said she was notified of the decision by prosecutors.

Skakel, a nephew of Ethel Kennedy, was convicted in 2002 of bludgeoning his neighbor, Martha Moxley, to death with a golf club in 1975 in wealthy Greenwich. Skakel, who along with the victim was 15 at the time, is serving 20 years to life in prison.

He appealed his conviction to the Connecticut Supreme Court last year, arguing among other things that the statute of limitations had expired when he was charged in 2000.

Dorthy Moxley, Martha's mother, told The Associated Press on Thursday that she was told by prosecutors that the high court had rejected Skakel's appeal. She said she was told that the decision would be announced Friday.

"I'm not at all doubtful Michael did this. I know he did this," Moxley said. "I hope this is the last we'll hear of them."

A prosecutor declined to speak publicly about the case while Michael Sherman, Skakel's trial lawyer, said he was surprised by news reports of the decision.

"Nothing will ever change my opinion that an innocent man is in jail," he said. "He's simply not guilty."

The defense had argued that, at the time of the killing, the statute of limitations was five years, so Skakel could not be prosecuted. Skakel also argued that the case should not have been transferred to Superior Court from Juvenile Court, where he was first charged.

Authorities have called the transfer from Juvenile Court "the only reasonable route," noting that Skakel was 40 when he was arrested.

The appeal also contended that prosecutors engaged in misconduct during closing arguments by calling Skakel a "spoiled brat" in an effort to inflame the jury. Further, the appeal criticized the prosecution for presenting a taped interview of Skakel that was played as a projected photo of a smiling Martha Moxley dissolved into a grim crime scene photo. Skakel's attorneys called the audiovisual presentation a "made-for-conviction movie."

Prosecutors said the closing argument was based on evidence and testimony from witnesses.

Skakel still has a petition for a new trial pending in Stamford Superior Court. In that appeal, a cousin of basketball star Kobe Bryant implicates two other men in the murder. Prosecutors have said they are skeptical of that claim.