Stephen Joseph Flemmi was born on June 9, 1934, in Boston’s Roxbury neighborhood, the first of three sons to Italian-American parents—Giovanni, a bricklayer and WWI Royal Italian Army veteran from Bari, and Mary Irene Misserville, born in Massachusetts to Italian roots from Ceccano, Lazio.The family lived at 25 Ambrose Street in the Orchard Park tenement, where young Stephen grew up in poverty and streetwise toughness.

He got into serious trouble early: arrested at just 15 for "carnal abuse," and sent to juvenile detention for assault. Yet in 1951, at age 17, he enlisted in the U.S. Army. He served two tours in the Korean War with the 187th Airborne Regimental Combat Team and earned both a Silver Star and a Bronze Star before being honorably discharged in 1955.

Back in Boston, Flemmi slipped back into crime. He and his brother Vincent joined the Roxbury Gang in the late 1950s under the Bennett brothers. Even though he was slim and soft-spoken, Flemmi earned a reputation as a ruthless enforcer. He ran operations out of the Marconi Club—part massage parlor, part brothel, part bookmaker—and became a recognizable figure in Boston’s criminal underworld.

By the 1960s, he was deep in organized crime and also informant territory. Working with detective William Stuart of the Boston PD, Flemmi got protection in exchange for info on rival criminals. 

Gang wars tore through Boston in the 1960s, and Flemmi was frontline. He allied with Whitey Bulger’s Winter Hill Gang and immigrant-friendly Patriarca family, committing murders and racketeering for both. 

Under FBI protection, Flemmi and Salemme assassinated the Bennett brothers—"Wimpy" on January 19 1967, Walter on April 3 1967, and Billy dumped and dead by December 22 1967—clearing their path for power and control. They also bombed attorney John Fitzgerald in 1968, wounding him severely, and reportedly killed Thomas Timmons for entangling with the Patriarcas.

By 1969, Flemmi was indicted for murder and attempted murder. But he and Salemme fled, and Flemmi even double-crossed Poulos—murdering him in the desert for fear he'd fold under pressure. He lived on the run for about 4½ years in Montreal, working quietly, while FBI handlers kept him sheltered and informed. In 1974, with charges dropped, Flemmi returned to Boston.

That’s when he and Whitey Bulger became both crime partners and co-informants—reviving the Top Echelon informant status under agent John Connolly. Together, they operated with impunity, supplying the FBI with intel on the Patriarcas while expanding their own criminal reach.

In the early 1980s, Flemmi’s violence turned disturbingly personal. He strangled Debra Davis—his former lover—on September 17 1981, removing body parts to avoid identification, and disposing of her near the Neponset River. Four years later, in 1985, he and Bulger murdered Deborah Hussey—his own stepdaughter and sexual abuse victim—burying her in a crawlspace and re-burying the body elsewhere as pressure mounted.

Throughout the 1980s, Flemmi and Bulger helped the FBI bug the Angiulo headquarters, which decimated the Boston Mafia—they were informants who destroyed their own rivals. Meanwhile, the FBI overlooked Flemmi’s direct involvement in murders, extortion, drug trafficking, and more.

Criminal justice eventually closed in. In 1995, Flemmi was arrested in Boston—famously asking, “Is this a gag?” as state police cuffed him. He tried to blame the FBI for protecting him, but without immunity that fallback failed. 

By October 2003, he pleaded guilty to 10 murders in exchange for transfer of benefits promised to his brother. Flemmi testified against Connolly and Bulger and ended up incarcerated under the Federal Witness Security Program (WITSEC).