NORTH ATTLEBORO - The state Supreme Judicial Court Thursday reversed a lower court's decision to grant Edward Lykus a new trial in the notorious 1972 murder of his 13-year-old neighbor and upheld his conviction.

In a 13-page decision, the court ruled that evidence favorable to Lykus which the FBI withheld from prosecutors would not have changed the outcome in the case because other evidence of his guilt was "overwhelming."

A Bristol County Superior Court judge in 2005 had ordered a new trial, saying that the FBI's decision to withhold a report regarding voiceprint analysis of a ransom call prevented Lykus from getting a fair trial.

Lykus was 20 when he was convicted in 1973 in the kidnapping and murder of 13-year-old Paul Cavalieri and extorting $50,000 from his family.

Lykus, now 55, the son of the late Police Chief Stanley Lykus, has always denied killing Cavalieri. But he admitted to picking up the ransom money, saying he was paid $500 from an unknown drug dealer. Evidence used in the case included voice print analysis of telephone calls to the victim's family, which were taped by authorities, demanding $50,000 in ransom.

Police also found bullets in his apartment which were the same caliber as those in the murder and staples similar to those included in the ransom note. When confronted by police with evidence, Lykus changed his story several times.

Lykus had lost previous appeals but later obtained FBI documents which revealed the bureau deliberately withheld a report questioning the reliability of the voice identification linking Lykus to the ransom call. The report was kept from state prosecutors.

In it's opinion, the SJC noted the undisclosed report did not repudiate the voice analysis or exclude the defendant as the speaker. It merely stated it was not definitely possible to determine the voice was the defendant's.

The report, the SJC said, may have only undermined an agent's testimony "in a minor way" and "would have done more damage to the defendant's wholesome attack on the suitability of voice spectrogram analysis in the court room."

The high court also noted seven witnesses who were friends of the defendant identified his voice and the evidence was properly admitted at the time.

"The defendant's effort to minimize the vast body of circumstantial evidence as 'equivocal at best' by questioning each segment severally, as if it had no relation to the other segments or to the case as a while, is totally unpersuasive," the SJC ruled.

Lykus' lawyer, Chauncey B. Wood of Cambridge, had argued evidence in the case was not as strong as the prosecution claimed, including statements by six witnesses who identified his voice.

Wood said the identification was flawed and "suggestive" because the witnesses, who were friends of Lykus, listened to the tape at the police station at the same time and in the same room.

He also said the only people were heard the caller were Cavalieri's parents, who also knew Lykus, and could not identity the caller. He also said argued the FBI played a major role in the investigation and its role in withholding evidence undermined the integrity, reliability and fairness of the criminal justice process.

"I think this decision is an injustice," Wood said, adding that he is considering a further appeal in the federal courts.

Gregg Miliote, a spokesman for Bristol County District Attorney Sam Sutter, said his office was pleaded with the ruling.

"We hope that this will bring some much needed closure to the victim's family," Miliote said.

"We believe, and the SJC agreed, that the judge erred in granting a new trial because of the overwhelming evidence of guilt in this case," he said.

Miliote credited prosecutors William Connolly and Rachel Eisenhaure and David Mark, chief of the appeals unit, for working "countless hours" on this case.