The Criminal Investigation Services will probe Tory complaints about "alleged impropriety" by former top staffers, said OPP Commissioner Chris Lewis.
"We're conducting a criminal investigation, so if there's no criminal charges, we'll be out of there," he said in an interview late Friday.
"If a criminal act did occur, then we'll try to prove who did it and lay charges accordingly."
The probe comes in the wake of a scathing report by the province's privacy watchdog that found top Liberals broke the law by deleting emails on the cancelled gas plants in Oakville and Mississauga.
Information and Privacy Commissioner Ann Cavoukian reported Wednesday that David Livingston, former premier Dalton McGuinty's chief of staff, tried as late as January to find out how to permanently delete emails related to the gas plants.
The opposition parties say the emails were wiped out to try to cover up the true costs of cancelling the gas plants, which has grown to an estimated $585 million, well above the $230 million the government had claimed.
It's a big blow to the Liberals, who've been engulfed in controversy for nearly a year over their decision to pull the plug on the plants — one of which was cancelled in the dying days of the 2011 election campaign.
McGuinty, who is still a sitting MPP, denied he had a hand in the deletion of emails.
"I was unaware of discussions between government staff and the Ontario Public Service regarding the deletion of documents," he said in a statement.
"And at no time did I condone or direct the deletion of emails or documents which ought to have been preserved."
Lewis said the first step will be for police to interview the people who made the allegations and then those who are named. But it's hard to say how long it may take before police determine whether any criminal charges should be laid.
"Our officers will follow the evidence and go as far as they need to either prove or disprove that something occurred," he said.
The OPP launched a criminal probe into financial irregularities at Ontario's Ornge air ambulance service over a year ago and no charges have been laid yet, Lewis said.
"When you start trying to retrieve data and conduct interviews, sometimes it takes much longer that what we see on TV when they wrap it all up in an hour and a half."
Premier Kathleen Wynne, who won the leadership contest in late January, has said that she'd co-operate with any investigation.
She also said that the mass email deletions were unacceptable and staff have been made aware of their record retention obligations.
The New Democrats are pushing for McGuinty to appear again before the legislative committee that's looking into the cancelled gas plants, saying he needs to explain under oath the deleted emails.
"Dalton McGuinty needs to come back and answer this new information from the privacy commissioner," said NDP energy critic Peter Tabuns.
In addition to McGuinty and Livingston, the NDP also want to hear from several other senior Liberals whose email accounts were deleted, including Craig MacLennan, the former chief of staff to the minister of energy.
Sitting members can't be compelled to testify at committee, but Tabuns said he expects Wynne to force McGuinty to show up.
"Kathleen Wynne has made it very clear that if people have questions about those emails with regard to the former premier, he should be asked," said Tabuns. "She should make sure that that member of her caucus appears and answers questions."
McGuinty announced his resignation as premier and prorogued the legislature last October, killing a contempt motion against former minister of energy Chris Bentley over the government's failure to hand over documents to the committee.
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