NORWALK, Conn. — A former resident of a Maine treatment center that Michael Skakel attended in the 1970s testified Friday that the Kennedy cousin claimed that he blacked out and was unsure whether he or one of his brothers killed Martha Moxley in 1975.

Prosecution witness Elizabeth Arnold of Massachusetts testified that Skakel was confronted about the killing during a group therapy session at the facility in Poland Springs, Maine, in 1978.

"It was about a girl in his hometown who had been murdered," Arnold told the jury in Skakel's murder trial. "He didn't know what happened that night. He was very drunk and had some sort of blackout. He didn't know if he had done it or his brother had done it."

Arnold did not mention any brothers by name. A jury has already heard that his older brother, Thomas Skakel, was the last person to be seen with Martha before she was killed.

Arnold offered testimony that tended to support the prosecution's theory that sibling rivalry was the motive for the murder.

"He said his brother f-ed his girlfriend," Arnold testified.

She went on to explain that it was her understanding that the unidentified brother did not have intercourse with Martha, but that the two teenagers had been "fooling around."

On cross-examination, Arnold conceded that she never mentioned anything about a brother being intimate with Martha or trying to steal Michael Skakel's girlfriend when she testified before a one-judge grand jury in 1998.

"I didn't recall it at the time," she said. Arnold also testified that after Michael Skakel ran away from Elan in 1978 he was brought back and faced a "general meeting," a much-feared gathering of his peers in which violators of rules were brow-beaten for hours.

Arnold said that Michael Skakel was also put in the "boxing ring" an exercise where other residents wore boxing gloves and head gear and pummeled the violator. "I know he was brutalized," Arnold said.

The defense contends that anything Skakel may have said to fellow Elan residents was a result of constant badgering, intimidation and physical abuse. Arnold is the fourth former Elan resident to testify since testimony began May 7. Skakel statements while at Elan are the centerpiece of the prosecution's case against the 41-year-old nephew of Ethel Kennedy.

Arnold said she did not believe Skakel killed Martha and tried to console him after the group therapy session in which he questioned whether he or his brother killed Moxley.

"He was very upset because he didn't know if he killed this girl. He was on the edge of tears … he was very pained," Arnold said. "He didn't think he did it, but [thought at the time] his brother did it."

Former staff member confronted Skakel

Elan graduate and former staff member Alice Dunn of Portland, Maine, told jurors that Skakel was drinking in a bar near Elan about eight or nine months after the general meeting when she brought up the Moxley murder.

Dunn said Skakel was pensive, looked down and avoided eye contact. "He was saying, 'I don't know what happened,' she said he told her. "'I don't know if it was me. I don't know if it was my brother because I don't remember everything. I just don't know.'"

Prosecutor Jonathan Benedict got Dunn to concede that during the grand jury she said Skakel told her at the restaurant that "as far as he was concerned he might have done it, but if he did do it, he was not in his right state."

Dunn said on cross-examination that it was her perception that Skakel truly did not know in 1978 whether he had killed Martha with a golf club three years earlier.

Dunn also recalled the incident at the general meeting when Skakel was put into the boxing ring and was confronted about the murder. "He kept saying, 'I didn't do it. I didn't do it. I didn't do it,' " Dunn said. "And every time he said he didn't do it, he was put in the boxing ring." Dunn said the exercise stopped when Skakel finally offered that he did not know if he killed his neighbor.

As part of his punishment for running away, Skakel was forced to wear a cardboard sign around his neck for six weeks, Dunn said. "The sign said, 'Confront me on why I murdered Martha Moxley,' " Dunn told jurors. Dunn was the 28th witness called by the prosecution, which is expected to rest late next week.

Judge rules records can't be admitted

In a hearing outside the presence of the jury Friday, prosecutors asked to call an Maine investigator to testify about his 1997 search for Michael Skakel's records from the Elan school.

Prosecutors wanted to show that the file was considerably thinner than those of other residents at the school, suggesting that perhaps somebody had removed records in order to protect Skakel. Sherman argued that the file and the testimony of the investigator were not relevant.

"It is the Kennedy conspiracy at work and it has no relevance to this case," Sherman said.

Judge John Kavanewsky agreed and did not allow the testimony.