SUDBURY, Ont. -- A federal NDP defector won a byelection Thursday in Sudbury, Ont., for the provincial Liberals, but the party's path to victory was marred by bribery allegations that are now under a criminal investigation.

Glenn Thibeault beat out NDP candidate Suzanne Shawbonquit and independent Andrew Olivier, who triggered a scandal after he was dumped by the Liberals in favour of Thibeault.

Olivier was the Liberal candidate in the June general election and lost by fewer than 1,000 votes to New Democrat Joe Cimino, who resigned the seat five months later, triggering the byelection.

Olivier alleges the Liberals offered him a job or appointment in exchange for stepping aside. He finished third Thursday, running as an independent. Olivier, who is quadriplegic and records many conversations in lieu of taking notes, released audio of his talks with two Liberals, including Sorbara.

The opposition parties said the Liberals' actions amounted to bribery and asked the Ontario Provincial Police and Elections Ontario to investigate.

OPP went to court to seek Olivier's original recordings and in a document they filed to get a production order, investigators say they believe the Liberals violated the Criminal Code, a Globe and Mail report said Thursday.

OPP Det.-Const. Erin Thomas says in the document that she "has reasonable grounds to believe and does believe" that there was a job offer that violates the Criminal Code, the report said.

Elections Ontario is also investigating the Liberals' alleged actions, which the opposition parties say amount to bribery.

Premier Kathleen Wynne would not comment on the police allegations as she left Thibeault's victory party, only vaguely referring in her speech to unpleasantness during the campaign.

"The thing I am the proudest of is that there was a lot of negativity in this campaign and you saw through that, you saw with your optimism, you saw the possibility, you ran a terrific campaign," Wynne told a cheering crowd of Liberals.

Thibeault later said the criminal investigation doesn't taint his victory.

"We're going to go celebrate," he said. "We won tonight and that's what we're going to be doing is getting right to work."

The Liberals have denied the bribery allegations, saying they were trying to keep Olivier involved in the party after Thibeault's appointment was already decided.

Thibeault's win means his decision to jump ship and the Liberals' gamble in appointing him instead of holding an open nomination paid off. The move rankled many in the community, with the local Liberal riding association executive quitting over the appointment.

"It got pretty negative, and we kept it positive," Thibeault told his supporters. "I know there's much work to do and there's bridges to rebuild and I'm fully prepared to do that."

The result of the byelection does not change the balance of power at Queen's Park, where the Liberals already controlled of majority of seats, but as a top Liberal told Olivier in one of his recorded conversations, Wynne was desperate "in a good way" to win back the Sudbury riding.

Before the last election the Liberals had held the seat for 19 years, so with the former stronghold in play again, Wynne showered attention on the riding, visiting six times since calling the byelection.

Thibeault captured 10,626 votes and Shawbonquit earned 8,985 while Olivier got 3,177.