Organized crime experts are speculating that the murder of alleged hitman Salvatore “Sam” Calautti, 40, at a stag party in suburban Toronto was revenge for the murder of 86-year-old mob boss Nicolo Rizzuto at his home on Antoine-Berhelet Ave. on November 10, 2010.

Calautti was among 100 people assembled at the party in Vaughn, Ontario when he was shot dead in his BMW at around 1 a.m. Friday.

His friend James Tusek, 35, was also killed in the shooting.

Vito Rizzuto, the current alleged Montreal mafia gang leader, was in prison in Colorado when his father, son, brother-in-law and several other associates were killed, some believe by Ontario-based underworld figures.

Calautti was part of a Calabrian clan, while the Rizzutos are Sicilians. The Rizzutos led a violent overthrown of the ruling Calabrian Violi clan in Montreal between 1976-80.

Calautti was a father of three and ran a pizza shop in Toronto but was also known as a brutal loan collector who was said to be a suspect in several murders.

Nicolo Rizzuto was killed by a sniper who snuck up to his house through a forested area and shot him through double-paned glass with a high-powered rifle, killing him instantly.

Montreal's La Presse newspaper and the Toronto Star have reported that a close associate of Calautti was detained and questioned by Montreal police following Rizzuto's murder.