By the early 1980s, Coulumbe moved to Montreal and joined the SS biker gang, where he became associated with Maurice "Mom" Boucher and Salvatore Cazzetta. With him, "Le Chat" brought along his extensive
The SS disbanded in 1984 and Coulombe, like several Missles before him, became associated with the Hells Angels Montreal chapter. By 1985, he was a prospect with the club. On March 23, 1985, Coulombe picks up firearms from Angels Robert "Tiny" Richard, Denis "Pas Fiable" Houle, and Jacques "La Pelle" Pelletier and delivers them to the Lennoxville clubhouse. The next morning,
he stands guard outside the building as five members of the North chapter are slaughter within.
Days after the murders, Coulombe and Normand "Biff" Hamel, on Réjean "Zig-Zag" Lessard's orders, rented two large trucks and emptied the North Chapter's Laval clubhouse and the murdered Angels apartments.
On June 26, 1985, Coulombe is told that he will receive his colors and be initiated into the club the next day. He called Hells Angels Gaétan "Gaet" Proulx and Jean-Paul "Donat" Ramsay, both of which he is close to, but neither knew anything about it. Coulombe began to worry that he was next on the hitlist.
The very next day, the Surete du Quebec SWAT team, armed with submachine guns, crashed into the prospect's room as he slept. He was taken into custody and when police questioned him, Coulombe broke down and decided to become the first biker in Quebec to inform against the Hells Angels.
With the information provided by Coulombe, and later Yves "Apache" Trudeau and Gilles "Le Nez" Lachance, 17 Hells Angels were charged with first degree murder on October 2, 1985. Gerry Coulombe testified against his former comrades and is living under a new identity somewhere in Canada.