Duchesneau, the former Montreal police chief hired by the Liberal government in 2010 to head its anti-collusion squad, has been portrayed as a symbol of integrity in Quebec.
The CBC French-language service Radio-Canada has reported that Duchesneau's long-defunct municipal party, Nouveau Montréal, failed to report around $50,000 in donations raised at an event at Windsor Station.
At the time, Duchesneau's party estimated some 2,000 supporters attended the event.
Anonymous donations were legal at the time, and Nouveau Montréal said in its annual report that it raised a little more than $2,500 at the event.
Radio-Canada spoke to four individual sources who said that the amount raised was actually closer to $50,000.
"My memory was that it was $57,000," said one man, who described himself as part of Duchesneau's "inner circle" at the time of his mayoralty bid.
"You counted it?" he was asked.
"I was present when it was counted," he replied.
A second source confirmed in a recorded telephone interview having watched people counting the money and said that it was more than $50,000.
Two other sources said they had heard from members of Duchesneau's party that about $50,000 was raised.
Allegations 'ludicrous,' Duchesneau says
Duchesneau, running under the CAQ banner in St-Jerôme, has called the allegations outlandish.
Asked if it was realistic to say that his party had raised only $2,500 at the 1998 event, Duchesneau said it was.
"I didn't know about the principle of passing the hat," Duchesneau said. "It was perfectly legal at the time. But people didn't give. They were friends. It was festive. It wasn't really a fundraising activity."
Radio-Canada also spoke to many people who had been Nouveau Montréal candidates and supporters, who described Duchesneau as a man of integrity and said they believe the party was financed legally.
Everyone interviewed, including the four sources, confirmed they were paid by cheque, not cash.
Duchesneau said he believes he is the victim of a smear campaign, either by people in other political parties who are threatened by Coalition Avenir Québec or by enemies he made when he headed the anti-collusion squad.
"I spent 18 months on the anti-collusion squad," he said. "We saved $348 million that would have gone into the pockets of people close to the Liberals. Do you think that I made friends doing that? The answer is no.
"Are people frustrated? Surely. Are people capable of inventing all kinds of things? Surely."
Duchesneau said if he had skeletons in his closet, he wouldn't have returned to the political stage.
He ended his 1998 mayoralty campaign approximately $368,000 in debt. It was settled by 2001.
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