A notorious hitman, John Martorano was at the center of much of the Winter Hill Gang's dirty work in the 1970s. The Milton native has admitted to committing 20 murders between 1965 and 1982, some allegedly at the direction of "Whitey" Bulger and Stephen Flemmi -- or with the gangsters' direct participtation.

Martorano was among the Winter Hill gangsters charged with fixing horse races in 1979 -- an indictment that left out the names of Bulger and Flemmi, thanks allegedly to the FBI's maneuverings.

Martorano fled Boston and spent 16 years on the run. He was finally arrested in Florida in 1995 and indicted on additional charges of money laundering and extortion. Law enforcement agents revealed to Martorano that his former partners had been betraying him to the FBI for years; Bulger had even tipped authorities that the hitman was hiding out in Florida.

Furious, Marorano cut a deal with prosecutors in 1999 in which he agreed to plead guilty to a string of murders and implicate Bulger and Flemmi as accomplices in exchange for a reduced sentence. Thanks in part to Martorano's testimony, Bulger and Flemmi now face murder charges in Oklahoma and Florida that could carry the death penalty.

This profile was written by the staff of Boston.com based on material from The Boston Globe archives.