"He was focused," he said. "He wasn't somebody who went out late at night and got drunk. He kept a very low profile in his personal life, not flashy or showy."
Bulger, who became the model for Jack Nicholson's sinister crime boss in the 2006 Martin Scorsese movie "The Departed," cultivated an image as a benevolent tough guy in his working-class neighborhood, someone who would help old ladies across the street and give turkey dinners for Thanksgiving. But as the bodies of his victims piled up, he was revealed as a ruthless killer.
Among the killings Bulger was accused of committing or orchestrating were two men who were chained to chairs for hours, interrogated, then shot in the head; two women who were strangled, including Davis; and two men who died in a hail of gunfire as they left a South Boston restaurant.
"He enjoyed killing," Massachusetts state police Detective Lt. Stephen Johnson said after Bulger's arrest. "We know from people who were there that post-murders, he would act super-relaxed. His associates said he would be in a good mood for a long time after he killed someone."
For years, investigators say, government corruption kept them from building a case against Bulger. In 1985, federal prosecutors tried to nail him for controlling betting and loan-sharking rackets in the Boston area, but no charges were filed.
At his trial, prosecution witnesses and Bulger's own lawyers said he gave payoffs to a half-dozen FBI agents, at least one state trooper and Boston police officers to get information on search warrants, wiretaps and investigations so he could stay one step ahead of the law.
In 1994, Bulger vanished. A former FBI agent, John Connolly, was later convicted of tipping off Bulger that he was about to be indicted.
William Bulger was forced to resign as president of the University of Massachusetts system in 2003 after it was learned he got a call from his fugitive brother and didn't urge him to surrender.
After more than 16 years on the run, Bulger was captured at age 81 in Santa Monica, Calif., where he had been living near the beach with his longtime girlfriend, Catherine Greig.
At the trial, with Bulger at last held to account for his crimes, he took notes on a legal pad and traded occasional profanities with the former associates testifying against him. But Long, the retired investigator, said the trial didn't reveal anything he didn't already know about Bulger, who faces life in prison.
"He looked," Long said, "like the self-absorbed psychotic that he is."
Melia reported from Hartford, Conn. Associated Press writers Bridget Murphy and Denise Lavoie in Boston contributed to this report.