Criminal investigations into party financing and political interference are targeting four Liberal members of the National Assembly who sat under Jean Charest, including one re-elected earlier this month and former Liberal deputy premier Nathalie Normandeau, according to Radio-Canada.

The separate revelations, one from an investigative report and the other from court documents released to several news outlets Wednesday, mark two new milestones in Quebec's ongoing scandal over political influence, party financing and the awarding of construction contracts: For the first time, a sitting Liberal has been implicated, and it's also the first time a high-ranking former cabinet minister has been named as a suspect.

The Radio-Canada report on the current Liberal caucus member under investigation, along with two others who have left politics, cited documents obtained from anonymous sources and did not name the members.

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Meanwhile, investigators for the anti-corruption squad known as UPAC allege in court documents unsealed Wednesday that Ms. Normandeau overruled underlings in the Municipal Affairs department in 2007 to grant a $11-million subsidy for a water-treatment plant in return for political donations.

Several Quebec media outlets, including Radio-Canada, fought for release of the documents. While investigators say breach of trust, fraud and conspiracy are among the crimes under investigation, they do not identify who might be charged. None of the allegations have been proved in court, and no criminal charges have been laid against Ms. Normandeau, who denied the allegations in a statement late Wednesday.

"During my entire career, I was never manipulated by anyone. … I would have never accepted that such a situation could happen. I always did my job with integrity, rigour and honesty," she said.

UPAC also confirmed that Violette Trépanier, the party's director of fundraising from 2001 to 2012, and other Quebec Liberal Party officials are targets of the probe.

In the documents, investigators allege that Ms. Normandeau authorized an $11-million subsidy for the plant on Feb. 13, 2007, to the city of Boisbriand over resistance from Quebec's Department of Municipal Affairs to pave the way for a major real estate development.

Evidence collected by investigators "tends to demonstrate a political intervention took place in awarding the subsidy to overhaul the water treatment plant in Boisbriand," said an affidavit filed by investigators.

"The awarding of this subsidy is the result of sustained political financing since 2005 and the exercise of politician influence from various players close to minister Nathalie Normandeau and the Quebec Liberal Party."

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The documents were filed in support of a search warrant application to authorize a raid on the Liberal Party headquarters on July 9, 2013. Ms. Normandeau did not run in the recent provincial election, but the raid was certainly an issue during the campaign, which saw the Liberals elected under rookie leader Philippe Couillard.

Hitches in court proceedings delayed the unsealing of the warrant until after the April 7 vote, leading to demands from Liberal opponents that the party reveal who was targeted by the search. So far, no members of the newly elected government have been identified.

The 30-page document cites a senior department bureaucrat describing irregularities in the treatment of the file, including an "abnormal and surprising" decision by Ms. Normandeau to go against department advice and award the $11-million.

Roche, the engineering firm that obtained the contract to design the water treatment plant, organized numerous political fundraisers and put up employees as straw men donors – people who would make individual donations and then be illegally reimbursed by the company – according to testimony at the Charbonneau inquiry.

Investigators say the high fundraising demands imposed by the Liberals under then-premier Jean Charest – $100,000 per year per minister, according to reports – forced ministers to seek out corporate donations, which are illegal.

The Charbonneau inquiry examining corruption has heard how Lino Zambito, the construction boss who built the plant, also took part in fundraisers for Ms. Normandeau. In one memorable bit of testimony, he once sent a dozen roses to the minister and treated her to a Céline Dion concert.