Rabih Alkhalil, 25, is wanted on a charge of first-degree murder in the death of John Raposo, who was fatally shot June 18 as soccer fans gathered at a gelato shop to watch a Euro Cup game.
"The whereabouts of Rabih (Robbie) Alkhalil is unknown at this point in time, however homicide investigators are actively attempting to locate him," Staff Insp. Greg McLane said Wednesday.
"We are seeking the public's assistance in locating Alkhalil so that he can be apprehended on the warrant for first-degree murder."
Police released a photo of Alkhalil, who is also wanted on drug and organized crime related offences by police in Quebec and Niagara Region.
He's known to frequent Ottawa and Montreal and may have contacts in Vancouver, investigators said, but they cautioned that anyone who sees him should call 911 and not approach him.
Police also released the names of two other men facing first-degree murder charges in the shooting. Nicola Nero, 36, of Niagara Falls, was taken into custody Wednesday and Martino Caputo, 39, of Toronto, was arrested Saturday in Germany.
Police say Caputo is being held by German authorities on a warrant for drug-related offences in Niagara Region and that extradition proceedings are pending.
"It has always been the belief of investigators that John Raposo was a victim of a targeted murder," McLane said.
"As a result of the continued investigation that belief continues today and it is alleged that the murder plot involves an aspect of organized crime."
Dean Wiwchar, 27, of Vancouver, has already been charged with first-degree murder in the attack, which came weeks after a public shooting in the food court of the Eaton Centre shopping mall claimed the lives of two people and injured several others.
Weeks after Raposo's death, gunfire erupted at a Toronto community barbecue on July 16, leaving a 14-year-old girl and a 23-year-old man dead and 23 wounded.
Such "brazen" attacks have a huge impact on people's lives and their communities, said McLane.
"When (people) go to areas to be festive to celebrate events and these types of things happen, it tarnishes people's perceptions of what they can and can't do and are they safe doing it," he said.
The investigation into Raposo's death continues, he added.