The findings of an independent investigation into the accusations, upon which the Liberal leader based his decision, will not be made public, party insiders say.
Nor will Trudeau go into detail Thursday, when he's expected to publicly confirm the expulsion of Montreal MP Massimo Pacetti and Newfoundland MP Scott Andrews.
Insiders say Trudeau's hands are tied by promises of strict confidentiality that were made to everyone who agreed to participate in the investigation, conducted by Toronto lawyer Cynthia Petersen at Trudeau's behest.
But the continued shroud over the matter will doubtless fuel lingering questions about the fairness of a process that has traumatized two female New Democrat complainants and destroyed the reputations and careers of two Liberal men.
Pacetti announced Wednesday that he's decided to jump before he's effectively pushed out of politics.
While he continued to maintain his innocence, he said the furor over the allegations has taken a toll on both his family and his ability to represent his Montreal constituents.
Consequently, he said he won't seek re-election.
Pacetti's announcement came on the same day Trudeau informed him and Andrews that they will be permanently booted from the Liberal caucus and won't be allowed to run as Liberals in the coming campaign.
"Being a member of Parliament is an extraordinary experience and a privilege, but there comes a time in every person's life when they need to take stock of what is best for the people they care about," Pacetti said in a written statement.
Trudeau had intended to speak privately to Andrews and Pacetti on Wednesday, before making a public statement Thursday, insiders said. But the news leaked.
Andrews said he was "astounded" to learn his fate through the media. He said he co-operated fully with the investigation and had waiting since Friday for a promised copy of Petersen's executive summary before the matter became public.
Andrews said he was "disappointed to learn that unscrupulous, unnamed sources have chosen to communicate through the media rather than respect the process and those affected by it."
Trudeau suspended the pair last November from the caucus after a female New Democrat complained directly to him that Pacetti had allegedly had sex with her without her explicit consent.
She also told Trudeau that another female NDP MP had allegedly been sexually harassed by Andrews.
Both Pacetti and Andrews have maintained they did nothing wrong.
Attempts to get to the bottom of the complaints have been frustrated by the fact there is no formal process for investigating misconduct complaints between MPs.
Last fall, Trudeau initially asked Liberal whip Judy Foote to speak privately with the two women and, as a result of that informal process, bounced Pacetti and Andrews from caucus.
At the time, he did not reveal the nature of the complaints or the names, gender or party affiliation of the complainants.
However, New Democrats confirmed the complainants were NDP MPs and angrily accused Trudeau of "re-victimizing" the women by making the matter public. Trudeau's attempts to win all-party support to create an independent process for investigating the complaints foundered while Pacetti and Andrews languished in limbo.
In December, Trudeau hired Petersen, a human rights specialist who has investigated sexual harassment complaints in the private sector. It is not clear if either of the women co-operated with her or whether she had to rely on notes taken during the complainants' meetings with Foote.
One of the alleged victims spoke on condition of anonymity to various media outlets, including The Canadian Press, late last November.
She said she agreed last March to go for a night cap in the hotel room Pacetti calls home while in Ottawa, where she alleged he made unwanted sexual advances and eventually had sex without her explicit consent.
During the confidential meeting with Foote, sources have told The Canadian Press that the woman acknowledged she did not explicitly say no to Pacetti and that she provided a condom. In the interview, she refused to comment on those details.
In a separate incident, sources have told The Canadian Press that the second NDP MP alleged that Andrews followed her home after a social event, forced his way through her door, pushed her against a wall, groped her and ground his pelvis against her. She ordered him to leave. He did.
Sources have said the woman further alleged that Andrews subsequently repeatedly harassed her verbally, calling her a "c--kteaser," among other things.
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