Gibbs agreed to cooperate with the investigation in exchange for a lesser sentence.
"He was quick to volunteer," Ponzi said. "We never caught him in a single lie. He somehow never got on the witness stand, so he hasn't been outed like many others."
Gibbs, who has an extraordinary ability to recall names, addresses and details, was key to the case, and subsequently became a source whom Ponzi relied to learn about the operations of gangsters across north Brooklyn, he said.
"He was responsible for helping cause the demise of the Fat Cat organization," he said. "He was one of the first upper echelon cooperators against them. He's a really bad guy, but those guys killed a parole officer and a police officer."
The federal prosecutors initially weren't going to charge him with the homicides, but the Queens and Brooklyn district attorneys objected so forcefully that he was also obliged to plead guilty to the five murders and two attempted murders, Ponzi said.
His cooperation was valuable enough that prosecutors spoke on his behalf at the sentencing, he said.