Nicholas Regali is a recently paroled mobster encountered by John Doggett during the FBI investigation into the stabbing deaths of two women, Rita Shaw & Ellen Persich.
Regali killed people for years in organized crime but the murders of those two women for his own kicks began to be his undoing. Ultimately, thanks to Stuart Mimms/Rudolph Hayes, Doggett learned Regali was involved in the murder of Doggett's son, Luke.
Nicholas Regali met with A.D. Brad Follmer to discuss his involvement with Luke Doggett's death. Regali denied any involvement but reminded Follmer that they owned him as long as they had the videotape of Follmer being bribed by Regali years ago in New York city.
Doggett went to confront the man and Regali spelled out what had happened as a hypothetical possibility.
The story is that he was a "businessman" who in the course of that business dealt with unsavory individuals. One of them, Robert Harvey, was a pedophile and had kidnapped Luke Doggett. When Regali walked in on Harvey with the boy, the boy saw Regali's face. He had nothing to do with the abduction and molestation of Luke but knew trouble would come his way for being seen by the boy. So he murdered Luke Doggett.
After confessing the truth as a hypothetical situation, he left the bar. Doggett drew his gun to follow Regali out and kill him but shots rang out immediately after Regali left. Doggett found Regali dead, shot through the eye, with A.D. Brad Follmer standing over the man. (TXF: "Release")