TORONTO -- A criminal investigation hanging over Ontario's Liberal government is expected to dominate the start of a new legislative session as provincial politicians return to the house Tuesday after a nine-week break.

Opposition parties weren't silent on other alleged government misdeeds last session, such as the deletion of documents in the former premier's office on the cancellation of two gas plants, but since the legislature broke in December, Premier Kathleen Wynne has found herself embroiled in a new scandal.

Wynne decided to appoint Glenn Thibeault, who left the federal NDP for the provincial Liberals, as the party's candidate for a byelection in Sudbury rather than pitting him against the previous Liberal candidate for the riding in an open nomination.

The spurned candidate, Andrew Olivier, alleges that the Liberals offered him a job or appointment to step aside for Thibeault. Olivier, who is quadriplegic and records many conversations in lieu of taking notes, posted audio online of his talks with local Liberal Gerry Lougheed and the premier's deputy chief of staff, Pat Sorbara.

The Ontario Provincial Police and Elections Ontario are investigating. The Liberals have maintained no specific offer was made to Olivier, saying they were trying to keep him active in the party.

Wynne has not faced questions from reporters since police filed a court document in which they say there are grounds to believe an offence was committed. She will likely be flooded with questions from the opposition during the session's first question period.

"It's our duty," says interim Progressive Conservative Leader Jim Wilson. "Frankly as a politician I'm not going to let the sons of guns bring down the whole noble profession of representing your constituents."

The Sudbury byelection investigation marks the third criminal probe involving the Liberal government; police are also looking into the deletion of gas plant documents and financial irregularities at the air ambulance service Ornge.

"I certainly hope that the session isn't all about scandal because the people of Ontario deserve much better...but for it not to be, this government needs to step up and take some responsibility for their behaviour," says NDP Leader Andrea Horwath.

This session will bring the government's new budget, which Horwath believes will include cuts to public services, as the clock ticks closer to the Liberals' self-imposed deadline of eliminating the $12.5-billion deficit by 2017-18.

Deb Matthews, president of the Treasury Board, has said the government is engaged in a line-by-line review of program spending, though she vowed there will be no "across the board cuts."

The government's Ontario Retirement Pension Plan legislation should also pass this session, as will stiffer penalties for texting and driving, says government house leader Yasir Naqvi.

As for the Sudbury byelection questions that are sure to arise, the matter is in the hands of the OPP, Naqvi says.

"People want their government to focus on things important to them: quality health care, good schools for our children, making sure that our roads are safe, that we have good-paying jobs, that we have retirement income security," he says.