Canada's most powerful crime family may have been knocked off its pedestal, after the son of the alleged head mobster was shot to death in a brazen attack in Montreal Monday, says an expert in organized crime.

Nick Rizzuto, the 42-year-old son of reputed crime boss Vito Rizzuto, was shot in broad daylight at close range while standing in Montreal's Notre-Dame-de-Grace district.

There were several witnesses in plain view of the shooting but police say they still don't have a description of the gunman.

Antonio Nicaso, who has made a career out of writing books on Canada's crime families, told CTV Tuesday the shooting poses an "unprecedented challenge" to the Rizzuto family power.

"The murder took place in the weakest moment of the Rizzuto crime family history," Nicaso said in an interview with Canada AM. "They look more like disorganized crime than a powerful organization."

Nicaso said the family started running into trouble after Vito Rizzuto was sentenced to 10 years in prison after being convicted of racketeering. He also pleaded guilty to being present at the 1981 murder of three members of the Bonanno crime family in New York -- a murder that was later made into a movie called "Donnie Brasco."

Rizzuto is currently serving his sentence in Colorado and is expected to be released in 2012.

The patriarch was a skilled diplomat in the underground criminal world since the 1970s, mastering negotiations between the Italian and Irish mobs as well as the Hell's Angels.

Nicaso said the shooting was nothing short of an attempt to wrestle power from the family.

Since Rizutto was thrown in jail, the family has been in disarray, Nicaso said. People in his organization have been staying away from using street gangs, which has caused some divide among the members of the Rizutto crime family.

"Vito Rizzuto used to use street gangs for the dirty work, but after he was convicted, not many people in his organization liked the idea to include street gangs in day-by-day operations," Nicaso explained.

The family's decision to work with some street gangs may have also caused friction with other street gangs, Nicaso surmised.

Observers say the recent firebombings of Italian cafes in Montreal could have something to do with that as well.

Nicaso said it's difficult to predict what will happen next.

"We don't know what they are thinking, this is a very tough moment," he said. "Under normal circumstances we should expect retaliation, but these are not normal circumstances because the Rizzuto crime family is in disarray. We don't know what is the next stage."

The family has refused to comment on the murder.

Nonetheless, the brazen and rare attack "probably" means that more gang violence is ahead, he said.

"To see a high ranking member of the Mafia gunned down (in Montreal) you have to go back to the 70s."