A former Canadian Attorney General has published documents to support their version of events in the SNC-Lavalin affair.
Jody Wilson-Raybould submitted the documents, including an audio recording, to a Commons committee to investigate the matter.
The files were publicly released on Friday and should increase the pressure on Prime Minister Justin Trudeau.
He spent weeks struggling to contain the effects of the controversy.
The liberal prime minister has been accused of pressuring Ms. Wilson-Raybould to demand a legal favor for SNC-Lavalin that would prevent a prosecutor. Instead, alternative fines are imposed like a fine.
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The Prime Minister lost two top ministers – including Ms. Wilson-Raybould, who resigned from the Cabinet in February – Canada's highest bureaucrat and a senior executive.
Mr. Trudeau has denied any wrongdoing by him or his employees, claiming that nothing unusual has happened.
But opinion polls show that the controversy shook the popularity of Mr. Trudeau and his government months before the parliamentary elections.
Published documents include an almost 18-minute audio recording of a telephone call in December between Ms. Wilson-Raybould and privy council clerk Michael Wernick about the persecution of SNC-Lavalin.
The former Attorney General and Attorney General stated that she had taken the "extraordinary and otherwise inappropriate step" to make the call without Mr. Wernick's knowledge, as she wanted a precise account of the conversation.
She said she was worried about what she saw as an attempt to interfere in the case.
There is a long back and forth between the two in the summons, while the senior official repeatedly notes that the prime minister is interested in the company's refusal to prosecute for an agreement.
Mr. Trudeau and his officials have stated that they are worried that thousands of jobs will be jeopardized if the engineering office is convicted.
She presses back and warns she warned the interview as inappropriate and continued communication on the matter could transcend the bounds of her independence as a prosecutor as a prosecutor.
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"Inclusion allows members of the committee to decide for themselves" whether or not they have been pressured by Mr. Wernick. Mrs. Wilson-Raybould writes.
Mr. Wernick resigned this month as Canada's top bureaucrat.
The Liberal-dominated Judiciary Committee had closed its investigation of the SNC-Lavalin affair earlier this month and said its goals had been achieved.
After the panel closed the investigation, Ms. Wilson-Raybould announced that she would provide more material to prove her testimony.
About 40 pages were published containing text and e-mail copies, as well as Ms. Wilson-Raybould's comments on her view of events.
The opposition parties had requested that Ms. Wilson-Raybould return to committee after her testimony against the bomb shell in February. There, she accused Mr. Trudeau and members of his inner circle of having spent months trying politically to interfere with the SNC-Lavalin cause.