Larose was a Canadian citizen and an associate of Ludger Duvernay.
Sometime in June 1834, Larose visited Edmund Bailey O'Callaghan at his home, sent by Duvernay to inform O'Callaghan of the date of their assembly on the 24th, with which they hoped to oppose the Château Clique, the organization through which the Templars acted.
Larose himself also attended the meeting, slipping inside the McDonnell house, unaware that he was being followed by O'Callaghan. The latter found Larose standing over two bodies, one dead and one unconscious. Larose explained that the unconscious man, a violinist at the party, had murdered the other, being an agent of their enemies, and that he had been forced to neutralize him.