TORONTO -- Ontario Provincial Police Commissioner Chris Lewis says it may take another year before charges, if any, could be laid in the criminal probe of Ornge.

Lewis says investigators have travelled throughout Ontario and outside Canada to interview more than 50 people.

He says they've also obtained 22,000 pages of documents in the course of their investigation, which started just over a year ago.

Speaking before a legislative committee, Lewis says there are fraud cases that have taken years to investigate and no charges were laid.

But he says he's confident that within a year, they'll know whether there will be criminal charges laid.

Ornge has been under fire for more than a year over sky-high salaries, financial irregularities and allegations of kickbacks.

Ornge's president and CEO testified earlier Wednesday that paying out nearly $2 million in bonuses has caused Ontario's troubled air ambulance service to slip into the red.

Bonuses were almost always paid in the past -- about 97 per cent of the time -- to managers and executives, said Dr. Andrew McCallum.

It's a "major reason" why a federal arbiter ruled that Ornge must pay out nearly $2 million in performance pay, he said.

Ornge -- which receives about $150 million a year from the government -- promised last year to cancel bonuses to all non-unionized staff, but a group appealed the decision and won.

The bonuses are causing Ornge to slip into the red with a $2.5 million deficit, McCallum said.

From now on, the rules will change, he said. Any bonuses for non-unionized staff will depend on whether they achieve certain "personal and corporate goals."

Ornge will give performance pay to 424 unionized and non-unionized employees this fiscal year -- an average of about $4,632 each.

The bonuses won't be awarded to anyone who worked for the now bankrupt entities of Ornge, board chairman Ian Delaney said in a letter to the government obtained by The Canadian Press.

Last August, the all-party committee heard that disgraced former CEO Chris Mazza received at least $1.4 million in compensation. He also received about $1.2 million in loans in a single year, according to documents tabled with the committee.

Mazza received $500,000 from Ornge Peel in July 2010, $250,000 from Ornge Global and another $450,000 from Ornge Global in July 2011, according to the documents, which also detailed his lavish expenses.

Ornge is seeking $500,000 plus interest from Mazza, alleging he defaulted on a loan that he used to buy a house in west Toronto.

In a statement of claim filed Jan. 22 in a Toronto court, Ornge alleges that Mazza sold the house without telling Ornge, and has "failed or refused" to repay the loan.

Ornge said bankruptcy trustees are pursuing repayment of other loans Mazza received. They recovered "partial payment" of the loans, as well as about $600,000 from the sale of Mazza's home, said Ornge spokesman James MacDonald.

Auditor General Jim McCarter has criticized the governing Liberals for failing to oversee Ornge, despite giving it $730 million over five years and allowing it to borrow another $300 million.

The Progressive Conservatives complained Wednesday that Ornge is not providing certain documents, such as banking records for Ornge's now-bankrupt, for-profit spinoff companies.

But Health Minister Deb Matthews said they're doing everything they can to comply with the committee's request for information.

"Some 500,000 pages of documents ... have been delivered to the committee," she said in the legislature.

"We also have another 1.5 million pages of documents that are being provided on USB sticks, so Ornge is complying fully and the ministry is as well."