Police have cordoned off a wooded area behind the Montreal home of slain mobster Nicolo Rizzuto, leading to speculation his assassin may have hid there before shooting his target.

Rizzuto was gunned down inside the mansion where he lived in north-end Montreal late Wednesday afternoon.

Montreal police say at least one shot was fired at the 86-year-old great-grandfather, reportedly while two female family members were at home.

Emergency services received a 911 call and Rizzuto was rushed to hospital where he was pronounced dead. His wife and daughter were treated for shock.

Pictures from the scene indicate that a bullet pierced the solarium and the patio door, striking Rizzuto while he was in his kitchen.

It's likely that police are probing whether Rizzuto's killer was "hiding in the woods nearby the house and waiting for the profile of Nicolo Rizzuto to appear and then to take that one shot and actually kill him," CTV's Genevieve Beauchemin reported.

His assassination marked the latest strike against an infamous criminal organization that has withered away as its senior members have been jailed, killed or simply disappeared over the past few years.

Peter Edwards, an organized crime expert, said the murder of Rizzuto represents the loss of a powerful leader who still held sway in the underworld.

"You can't help but be shocked when an 86-year-old is murdered, but on the other hand his influence was enormous," Edwards said during an interview in Toronto on Thursday morning.

"I talked last night to someone who did a lot of enforcement work for him and he said that (Rizzuto) still was ‘the guy.'"

But police say there are other people who are jostling for power within the underworld.

"We know that Mr. Rizzuto was an important member of the Italian Mafia but new players have surfaced in recent months," Montreal police Cmdr. Denis Manville said Wednesday.

"There's a permutation (within the Mafia), not just here, but in other parts of Canada and abroad too."

The fact that he was killed at home with family members nearby signaled that Nicolo Rizzuto "had really become a disgrace in the eyes of the Montreal Mafia," said Pierre de Champlain, a retired RCMP organized-crime analyst.

"In the Sicilian Mafia, when we want to kill a leader, usually it's done in public and face-to-face. It's never done in the house and even less often with family members present," he told The Canadian Press.

His murder has garnered attention in many Italian newspapers, another indication of the significant profile Rizzuto had within the underworld.

"With the death of its historical patriarch the clan from Sicily has suffered a blow that could prove fatal," said a report from Italy's Ansa news agency.

Journey to the top

Rizzuto immigrated to Canada in 1954. He hailed from a small town in Sicily and could not read English.

But two decades later, he was part of a coup that wrestled control from a competing mob family, creating an opportunity for Rizzuto to build his own power base. He built ties to mob families in Italy and in New York, as well as to drug traffickers in South America and to Canadian biker gangs.

His son, Vito Rizzuto, was eventually jailed for racketeering, after admitting his part in a 1981 triple-slaying in a Brooklyn social club, in which three Mafia captains were killed. The incident was later recounted in the Hollywood movie "Donnie Brasco."

Vito Rizzuto, now 64 years old himself, remains in custody in a Colorado prison. He is due to be released from custody in a year's time.

Nicolo Rizzuto is believed to have held connections in illegal and legal businesses on different continents.

But his success has come with a heavy price, as police cracked down on his activities over the years and rivals have murdered many family members and colleagues.

The last year of Nicolo Rizzuto's life was filled with many such tragedies.

Last December, Nicolo Rizzuto's namesake grandson was gunned down in broad daylight, as he stood beside a car on a Montreal street.

The younger Nicolo "Nick" Rizzuto was only 42 years old when he died. His funeral in the city's Little Italy neighbourhood was attended by hundreds.

Vito Rizzuto, the jailed father of the murdered grandson, was not present at his son's funeral. It is not known if he will attend his father's funeral either.

In February, the elder Nicolo Rizzuto pleaded guilty to tax evasion in a Montreal court. He agreed to pay a $209,000 fine after admitting to the Canada Revenue Agency that he failed to declare interest on money he had stored in overseas bank accounts.

In May, Paolo Renda, the 70-year-old son-in-law of Rizzuto, was on his way home for dinner when he disappeared. His car was found only two blocks from his home, with the keys in the ignition and the doors unlocked. He has not been found.

At the end of June, Agostino Cuntrera, another one of Rizzuto's key associates, was shot dead as he walked out of a food distribution warehouse in Montreal's east end. A bodyguard died in the same attack.

The bottom line, it seems, is that someone "wants to remove the Rizzuto crime family from the Canadian underworld map," said author and Mafia expert Antonio Nicaso.

"In Montreal there's no war. The victims are all on one side," he said.

"It's like the end of an era in the Canadian underworld."

With a report from CTV Montreal's Stephane Giroux and files from The Canadian Press