OTTAWA — If Prime Minister Justin Trudeau had any thought that a burgeoning political scandal could be quietly contained, that hope vanished on Thursday, as Canadians dissected the explosive testimony from his former justice minister before a parliamentary committee.

“I don’t think I’ve ever seen a minister strafe her own government like this,” said Andrew MacDougall, who was the spokesman for Stephen Harper, the Conservative prime minister Mr. Trudeau replaced in 2015. “It just reinforces people’s perception that all politicians are kind of bent.”

During nearly four hours of testimony before the House of Commons justice committee on Wednesday evening, the former minister, Jody Wilson-Raybould, repeatedly contradicted and undermined Mr. Trudeau’s assertions that neither he nor his staff acted improperly in trying to settle a criminal case against SNC-Lavalin, a multinational construction and engineering company based in Montreal.

[Latest update: Trudeau promised a fresh approach to politics. Now he’s embroiled in scandal.]

Ms. Wilson-Raybould’s description of 10 meetings, 10 conversations and a series of emails about the criminal case from senior government officials dominated social media and news coverage in Canada on Thursday, as Andrew Scheer, the Conservative opposition leader in Parliament, asked the Royal Canadian Mounted Police to open a criminal investigation of the matter.