A close associate, housemate, business partner, and confidant of Shanley's for decades, White was a potential witness in both the criminal and civil cases involving the priest, who is alleged to be one of the most egregious abusers in the scandal involving Boston clergy, said Roderick MacLeish Jr. MacLeish is a lawyer for the Boston firm Greenberg Traurig, which represented hundreds of alleged clergy sexual abuse victims in claims against the Archdiocese of Boston.

Because he was so close to Shanley, who is free on bail awaiting trial on multiple counts of child rape in Middlesex County and whose alleged abuse is the subject of several civil cases expected to go to trial this year, White may have been the most tantalizing potential witness against the priest, MacLeish said.

After White relocated to Thailand from Billerica two years ago, the chance of forcing him to testify became extremely remote, MacLeish said.

Even if he could have been forced back to the United States to be a witness, MacLeish said, lawyers in the case thought it likely that White would refuse to testify and claim his right against self-incrimination.

That possibility became almost a certainty last September, when the first alleged victim to accuse White of sexual abuse stepped forward, MacLeish said.

"We always agreed that he had critical information, but the likelihood that he would testify was remote because he was going to take the Fifth Amendment," MacLeish said.

MacLeish declined to identify the client who has accused White, except to say that it is a man who alleges that both Shanley and White raped him during the 1970s when he was a boy.

The 72-year-old White, who had retired from the priesthood, died in Bangkok some time last week, said the Rev. Christopher Coyne, a spokesman for the archdiocese. Church records and published reports suggest that White and Shanley had a long association, going back to the 1960s when they served together at St. Patrick's Parish in Stoneham and then in the 1970s when both were street ministers at Warwick House in Boston's Roxbury neighborhood.