Kennedy cousin Michael Skakel felt his brother had stolen the affections of neighbor Martha Moxley, a former classmate testified Friday, offering a possible motive for the 1975 slaying of the 15-year-old girl.

Skakel — a 41-year-old nephew of Robert F. Kennedy's widow, Ethel — is charged with bludgeoning Moxley to death with a golf club in their wealthy Greenwich neighborhood in 1975. Skakel and Moxley were both 15 at the time.

Prosecutors Friday also read into the record testimony from Gregory Coleman, who died after using heroin last year. Coleman claimed Skakel once told him: "I'm gonna get away with murder. I'm a Kennedy."

Investigators have said both Michael and his older brother, Thomas, were romantically interested in Moxley.

Elizabeth Arnold, a classmate of Michael Skakel's during the 1970s at the Elan School, a substance abuse treatment center in Maine for young people, testified that Skakel felt his brother "stole his girlfriend."

"He said they didn't really have sex, but they were fooling around," she said.

Arnold said the issue came up in a small-group discussion at Elan, when classmates asked Skakel about the slaying.

"He said he didn't know what happened that night, he was very drunk and had some sort of blackout, and he had done it or his brother had done it," Arnold said.

On cross-examination by defense attorney Michael Sherman, Arnold acknowledged that she had not mentioned the comments when she testified before a one-judge grand jury that investigated the case.

She also acknowledged that she recalled the comments after reading a book about the Moxley case by former Los Angeles Detective Mark Fuhrman that speculates on a jealousy motive.

Arnold and another former student, Alice Dunn, described an intense meeting at Elan that Arnold said occurred a few days before the small-group session. At the session, Arnold said, Skakel was put in a boxing ring with other residents and was "brutalized"

Dunn said Skakel was dragged into a room full of classmates and Elan staff. School director Joseph Ricci brought up the murder allegation.

Skakel "said for at least a half an hour, `I didn't do it.' Every time he said he didn't do it, he was put into a boxing ring," Dunn said.

Eventually, Dunn said, Skakel said he didn't know whether he had killed Moxley.

Under cross-examination, she said the beatings would stop when Skakel changed his responses from denial to "I don't know."

Dunn also said Skakel was sometimes made to wear a sign saying, "Confront me on why I murdered Martha Moxley."

Dunn described other encounters with Skakel in which he said he didn't know what happened that night. In one incident at a restaurant outside of Elan, Skakel said, "I don't know if it was me, I don't know if it was my brother."

Also Friday, the pretrial testimony of the late Gregory Coleman was read into the record.

Coleman, who was at Elan with Skakel, died last August after using heroin. During a hearing four months earlier, he said he had been assigned to watch Skakel after Skakel tried to run away from Elan.

Coleman said he told Skakel it seemed he was getting special treatment. Coleman said Skakel responded: "I'm gonna get away with murder. I'm a Kennedy."

Coleman said Skakel then told him he had made advances on a girl who spurned his attentions.

"He made the comment that he drove her head in with a golf club. He indicated that he hit her so hard that the golf club had broken in half," Coleman said.

During cross-examination, Coleman admitted that he had been high on heroin when he testified before the grand jury about Skakel's comments. But he stood by his testimony about Skakel's comments.