Police had issued a Canada-wide warrant for 28-year-old Kyle Gabriel in early August.
He was wanted for two first-degree murder charges in connection with the shooting that killed two people at Flawnego Fashion on Saint-Jacques Street West March 8, 2010.
Isaac Regis and Terrell Smith have already been charged in connection with the shootings, they appeared in court in Montreal on Sept. 10.
Gabriel is set to appear in Montreal court Saturday.
Shooting believe to be gang retaliation
The shooting was believed to be a response to the December 2009 slaying of the son of reputed mob boss Vito Rizzuto.
Masked shooters opened fire in the upscale clothing shop just after lunch hour.
The boutique's owner, Ducarme Joseph, was arrested for violating bail conditions related to previous charges of fraud and extortion, sources said.
Investigators believe Joseph was the intended target of the attack. There are reports he slipped out the back door of the Flawnego boutique during the shooting.
According to court documents filed by police, Joseph is a reputed street gang leader and also acted as an enforcer for a Montreal real estate developer.Suggest a correction