BOSTON – The state’s highest court on Friday denied an appeal in the 1967 murder conviction of George Nassar, a remorseless killer who was the jailhouse confidant of the reputed Boston Strangler.

Nassar’s appeal before the Supreme Judicial Court came after his case lay dormant for more than 20 years. During that time, Nassar was implicated by various people close to the case as the real Boston Strangler, who killed 13 women between 1962 and early 1964.

He has denied he had anything to do with the deaths, and his attorney, Claudia Bolgen, repeated the denial Friday.

Nassar, now 75 and serving a life sentence, was 15 when he killed a Lawrence store clerk in 1948. He was paroled in 1961, then charged in October 1964 with shooting an Andover gas station attendant to death as the man begged for mercy.

Nassar’s case before the state’s highest court concerned a motion he filed to indicate his intention to appeal the 1982 denial of a new trial in the second killing. But he never acted, and the matter was dismissed in November 1983.

In 2006, Nassar, known for an extraordinarily high IQ, argued in court filings that he couldn’t make his case because he was in federal prison in Leavenworth, Kansas, without access to Massachusetts legal materials.

The court noted Friday that Nassar was back in Massachusetts in December 1983 and didn’t inquire about the case then or for more than two decades after.

Bolgen said she was disappointed in the decision, but said Nassar had a pending motion for a new trial in Essex County that she was confident would be granted.

The motion claims the judge gave erroneous jury instructions, including one involving a witness photo identification, and questions whether Nassar was advised of his right to testify, Bolgen said.

Bolgen said she could not comment on why there was such a gap in litigation in the case, but said Nassar is innocent of the 1964 killing.

“We’re hoping for justice, that’s all I can say, even after this late date,” she said.

While in jail, Nassar befriended Albert DeSalvo, who had been arrested for sexual assault in November 1964. The next year, Nassar told his attorney F. Lee Bailey that DeSalvo, another client of Bailey’s, was the Boston Strangler.

DeSalvo then confessed in remarkable detail to Bailey, who told the story in court in hopes of convincing the jury considering the sexual assault charges that DeSalvo was insane. It didn’t work, and DeSalvo was convicted and sentenced to life in prison.

DeSalvo later recanted his confession and was killed in prison in 1973. In 2001, forensic scientists announced that DNA evidence taken from the body of the strangler’s final victim didn’t match DeSalvo’s.

Ames Robey, a former prison psychologists who analyzed both DeSalvo and Nassar, has said Nassar was a misogynistic, psychopathic killer who was a far more likely suspect than DeSalvo. Some followers of the case said Nassar was the real strangler and fed DeSalvo details of the murders so he could confess and gain notoriety.

In a 1999 interview with The Boston Globe, Nassar denied involvement in the strangler murders, but said the speculation killed any chance he had for parole.

“I had nothing to do with it,” he said. “I’m convicted under the table, behind the scenes.”

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