You could hear the ticking of the clock hanging in the back of the courtroom and the cries of the seagulls that circled above Boston as the jurors – averting their eyes for the first time in the 50-day trial — filed past the six men in the dock. The day before, the six had been convicted in the slaying of a local hood named Edward “Teddy” Deegan. The jury was now being asked to choose between a sentence of life behind bars or death.

His voice flinty, 73-year-old Justice Felix Forte addressed the first four defendants in turn. “You are sentenced to die in the electric chair.” Undulating his hands to illustrate the chair’s 2,000-volt current, he added, “On the designated date, the electricity will run through your body until death.”

Joseph Salvati, a 35-year-old father of four young children, was next. Convicted of being an accessory to the murder, he rose uneasily to his feet. Forte asked if he had anything to say. Although Salvati had maintained his innocence from the beginning, he mumbled, “No.”

“You are sentenced to Walpole Prison for the rest of your natural life, without possibility of parole,” the judge said on that day, July 31, 1968. It was a death sentence of a different kind.

And it was especially harsh because Salvati — and three of the other five defendants — were innocent. Worse still, the FBI knew it all along.