All of the men accused in the murder of Salvatore "The Ironworker " Montagna have pleaded guilty to conspiracy.
Vittorio Mirarchi, Jack Simpson, Calogero Milioto, Pietro Magistrale, Steven D'Addario and Steven Fracas, pleaded guilty to conspiracy to murder, but no one has admitted committing the act of murder itself.
The men will return to court on June 10 for a sentencing hearing. Each of them faces a maximum penalty of life in prison.
A seventh man, Felice Racaniello, has pleaded guilty to accessory after the fact.
Last year Raynald Desjardins pleaded guilty for his role in the conspiracy to kill the mafia leader.
Montagna was killed in broad daylight on Nov. 24, 2011 in Charlemagne, near Montreal.
Witnesses saw Montagna running for his life as he jumped out of a white van and tried to swim across the river.
He was unconscious when police officers arrived at the scene minutes later, and died in hospital.
Desjardins survived an assassination attempt earlier in 2011.
Police say the attack on Desjardin and Montagna's murder were part of a power struggle to fill the void left by the breakup of the Rizzuto clan.