A witness at a hearing to determine whether Kennedy nephew Michael Skakel should be tried for the 1975 murder of a Greenwich teenager testified Wednesday that he was using heroin when he told a one-judge grand jury that Skakel confessed to the killing.

But the witness — Gregory Coleman, who was a student at a Maine treatment center with Skakel when they were younger — did not recant his testimony that Skakel confessed to the beating death of Martha Moxley.

Coleman has said Skakel told him he shattered Moxley's skull with a golf club and declared: "I'm gonna get away with murder. I'm a Kennedy."

Under questioning Wednesday, Coleman said he was under the influence of heroin when he made the comments about Skakel to the grand jury and during a television interview.

Coleman was being cross-examined by Skakel's defense lawyer, Michael Sherman, about inconsistencies in his testimonies.

"I was on drugs when I came before the grand jury," Coleman said Wednesday.

"That's kind of scary," Sherman replied.

Coleman said he used the drug at a hotel before he spoke to the one-judge grand jury which investigated the case and recommended that Skakel be prosecuted.

Coleman also said during he had used heroin and crack cocaine before a TV interview in which he said Skakel had confessed.

"Are you on drugs now?" Sherman asked Wednesday.

Coleman said he wasn't. "Give me a urine test," he said.

"No thanks," Sherman said, drawing a reprimand from the judge.

The hearing that began Wednesday is intended to determine whether sufficient evidence exists to try Skakel for the murder of Martha Moxley, whose body was discovered in October 1975 on her family's Greenwich estate.

No arrests were made for more than 24 years. Skakel, 40, was charged in the killing in January 2000 and later arraigned as a juvenile. A judge ruled in January that Skakel should be tried as an adult.

Skakel is the son of Rushton Skakel, the brother of Robert F. Kennedy's widow, Ethel.

An earlier probable cause hearing in juvenile court had focused on alleged confessions Skakel made while a resident at the Elan School, a substance abuse treatment center in Poland Spring, Maine.

One student, John Higgins, said Skakel confessed to him 20 years ago during an erratic, tearful conversation. But Higgins admitted he lied to investigators when they first asked him about the alleged confession. He also admitted asking about a $50,000 reward in the case.

During Higgins' testimony, tears trickled down Skakel's face.

"He's just very upset about hearing this moron get up there and lie," Sherman said at the time.

Coleman has previously admitted to a long battle with drug addiction, alcoholism and homelessness, at times living under a bridge.

Two other Elan students testified for the defense that they never heard Skakel confess.