MONTREAL, Que. -- Quebec's corruption inquiry has ended its 2013 public hearings after focusing on several themes, including corruption in the construction industry, illegal political financing and union infiltration by organized crime.

Inquiry chair France Charbonneau said Tuesday the probe will continue studying organized crime in the construction industry in January before switching to other topics of interest.

She said their nature of those topics would be made clear in the future.

In recent weeks, the inquiry zeroed in on the Quebec Federation of Labour, its powerful construction wing and its $9.3-billion union-investment fund, which was allegedly targeted by mobsters.

After being pressed for time earlier this year, the inquiry saw its mandate extended by 18 months until April 2015.

As part of that extension, Justice Minister Bertrand St-Arnaud asked for an interim report by the end of this coming January to give the government ideas on how to proceed with laws and policy.

The interim report is due Jan. 31, 2014.

After spending much of the past month in publication ban, Charbonneau issued a farewell statement on Tuesday to signal the end of the fall session.

Earlier this year, the inquiry heard from a wide array of witnesses, including engineering executives, city councillors, mayors, construction bosses and city officials.

They touched on everything from illegal political party financing, to engineering firms colluding on contracts, to organized crime's tentacles in the industry.

The inquiry, a major media spectacle when the hearings have been public, spent much of the past month under publication bans.

Charbonneau, a Quebec Superior Court justice who is overseeing the inquiry, said the bans are meant to protect criminal cases underway.

"We didn't have a choice," she said, adding the public is always invited to attend hearings in person if they want to know what's going on.

She said most of the testimony will eventually be released and published on the inquiry's website, as soon as it is legally possible to do so.

"For the moment, I assure you that everything that could be released publicly has been," said Charbonneau.

The public hearings resume Jan. 13.