Nick Rizzuto, seen here during his November 2006 arrest, pleaded guilty to two gangsterism-related charges Thursday in a Montreal court. (CBC)

The presumed patriarch of Montreal's Mafia and five associates have pleaded guilty to gangsterism-related charges.

Nick Rizzuto, 84, pleaded guilty Thursday along with five of his associates connected to Montreal's Mafia criminal underworld: Paolo Renda, Francesco Arcadi, Lorenzo Giordano, Francesco Del Balso and Rocco Sollecito.

Together, they faced more than 60 charges, including conspiracy to import and export narcotics, drug trafficking, bookmaking, operating illegal gaming houses, gangsterism and extortion.

But after reaching a plea bargain with the Crown, Rizzuto pleaded guilty to possession of proceeds of a crime, and possession of the proceeds of crime for the benefit of, the direction of, or in association with a criminal organization.

His son-in-law, Renda, 69, pleaded guilty to the same charges.

The plea bargain "serves the interests of justice, the public's interest, and avoids a long and costly trial that could have easily lasted six months," said Crown prosecutor Yvan Poulin.

Arcadi, 54, pleaded guilty to conspiracy, which included an admission he plotted to oversee drug smuggling and trafficking, bookmaking and illegal gambling.

Del Balso and Giordano pleaded guilty to similar charges, along with extortion.

Details about each man's involvement in the charges will be revealed when sentencing arguments are heard Oct. 16, Poulin indicated.

Police evidence includes wiretaps

Sentencing arguments could take some time given the summary of evidence in the case is about 400 pages long.

Sentencing will likely include some prison time and "financial consequences, heavy penalties, we're talking about confiscating goods and money," said Isabelle Richer, legal affairs correspondent for CBC's French-language service.

"That's what hurts criminal organizations, and there were many Revenue Canada investigators" attending the Thursday court hearing, she said.

The six men were arrested during Operation Colisée, a massive four-year police investigation that ended with raids in November 2006 that targeted more than 70 alleged members of Montreal's Mafia organization.

Police said they collected overwhelming evidence, including more than one million taped conversations obtained by wiretap, and 191 videotapes of alleged criminal activity that took place at a café in St-Leonard, a borough in northeast Montreal.

The videotape evidence showed the men counting large piles of money in a back room of the café.

The men are all in custody at the Montreal Detention Centre, formerly known as the Bordeaux Jail.

Rizzuto spent several days in hospital in April 2007 suffering from chest pains.

His son, Vito Rizzuto, once considered the godfather of Montreal's Mafia, is serving a 10-year prison sentence in the United States for his role in the 1981 murders of three captains of the notorious Bonanno crime family.

With files from the Canadian Press