MONTREAL -- The Crown has stayed charges against 36 people who were arrested in a massive anti-Mafia bust in Quebec on suspicion of arson, kidnapping and drug- and weapons-related offences.

A federal prosecutor said Tuesday her office conducted an exhaustive review of the charges in the RCMP-led Project Clemenza and used its discretion to end the proceedings.

Sabrina Delli Fraine told reporters that numerous factors played a part in the decision, including a recent Supreme Court ruling that set strict time limits for cases to get to trial.

Montreal La Presse, which reported Monday about the stay of proceedings, said the Crown's decision was based on the quality of the evidence and the techniques used to gather it.

At the time of the first wave of arrests, the RCMP proudly boasted about the tactic, which saw more than one million private PIN to PIN BlackBerry messages intercepted between 2010 and 2012 and analyzed.

But the prosecutor remained intentionally vague in her responses Tuesday, speaking of "unprecedented legal questions."

"They are legal proceedings that raise questions that are complex, complicated and without precedent that led us to make the decisions we made," Delli Fraine said.

Given that police and prosecutors worked on the investigation over several years, the decision to stay the charges was made after much reflection, she said.

Clemenza was the biggest anti-Mafia police sweep by federal authorities since its takedown of the Rizzuto crime family during Operation Colisee in 2006.

Clemenza was carried out over a series of busts against organized crime between 2014 and 2016 that led to dozens of arrests.

The suspects in question faced an array of charges, including trafficking, importation and production of drugs, and others related to weapons, arson and kidnapping.

Delli Fraine said the Crown can refile new charges in the cases within 12 months should the evidence warrant it.

The Crown will maintain cases against 11 other accused, with proceedings to resume May 23 when prosecutors believe they will be ready to divulge evidence to those charged, she added.

Of the 36 stays, one was delivered for an accused who has died.