Nicolo Rizzuto, the father of purported Montreal mobster Vito Rizzuto, has been shot and killed in his own home, sources have confirmed.

Rizzuto's death marks yet another blow to the Rizzuto family, which has had its grip on the Montreal underworld weakened over the last year.

In January, Rizzuto, 86, attended the funeral service for his 42-year-old grandson, Nick, who was named after his grandfather.

Nick Rizzuto was gunned down three days after Christmas, while he stood beside his Mercedes on a Montreal street.

Nicolo Rizzuto's son -- and Nick Rizzuto's father -- Vito, is currently serving a 10-year prison sentence in the U.S. for racketeering.

Earlier this summer, Agostino Cuntrera and a man reported to be his bodyguard were gunned down in the city in broad daylight. Cuntrera, 66, was believed to have been serving as head of the mob in Montreal following Vito Rizzuto's arrest.

And Paolo Renda, Vito's brother-in-law and right-hand-man to Nicolo, was reported missing in May and is presumed kidnapped. The 70-year-old's car was found abandoned near his home, which is on the same street, Antoine-Berthelet Ave., as the elder Rizzuto.

Antonio Nicaso, who has written several books about the mafia and is currently working on a biography of Vito Rizzuto, said Wednesday it is unclear who has been targeting members of the Rizzuto family. Whoever it is likely wants control of the industries the family is purportedly involved in, he said.

"I think they want to put their hands on the narcotics trade (and) on the extortion business," Nicaso told CTV News Channel Wednesday evening. "But most of all, on the largest ever infrastructure program … on everything from hydroelectric projects to roads and bridges."

Quebec is in the middle of its highly touted multi-billion-dollar ‘Infrastructures Plan' that encompasses both new projects and improvements to existing roads and buildings, which Premier Jean Charest has called "the largest renovation project in Quebec history."

Nicolo Rizzuto had been on probation after receiving a suspended sentence for crimes he pleaded guilty to in 2008.

Rizzuto pleaded guilty to possessing goods obtained through criminal gains and possession of proceeds of crime for the benefit of a criminal organization. He was arrested in 2006 on those charges during a police investigation dubbed "Colisee."

Earlier this year, Rizzuto pleaded guilty to two charges of tax evasion in a Montreal court. He had been accused of failing to declare interest revenues from more than $5 million he deposited to Swiss bank accounts in the mid-1990s.

Revenue Canada investigated Rizzuto and found that in 1994 and 1995, he failed to declare $627,906 in interest.

The Canada Revenue Agency said Rizzuto paid a $209,000 fine and settled his tax debts. He had also worked out a deal to pay back taxes and other penalties.