Open this photo in gallery Rick Dykstra, President of the Ontario PC Party, arrives for a meeting to pick an interim leader to lead them into the June provincial election at Queen's Park in Toronto on Jan. 26, 2018. The Canadian Press

Former top Conservative Guy Giorno says an independent investigation into the federal party’s handling of sexual-assault allegations against former Tory MP Rick Dykstra is a “sham” and he has no confidence in the results.

Mr. Giorno, who was Stephen Harper’s national campaign chair for the 2015 federal election, took direct aim on Friday at lawyer Carol Nielsen, who is leading the third-party investigation into the party’s handling of the allegations against the former Tory MP.

“It’s a sham process,” Mr. Giorno told The Globe and Mail. “I have no confidence in [Ms. Nielsen], I have no confidence in the results.”

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Mr. Giorno’s latest comments threaten to undermine an investigation that has already unveiled deep fractures in the party, since revelations that top Conservatives, including Mr. Harper, kept silent about the allegations even as Mr. Dykstra rose in the ranks of Ontario politics. Mr. Dykstra has denied the allegations.

Ms. Nielsen had invited Mr. Giorno to share any information he might have with the investigation. They arranged to meet in person on Friday.

Mr. Giorno, now an Ottawa-based anti-bribery and corruption lawyer, accused Ms. Nielsen of being biased towards him. In a series of tweets, Mr. Giorno claims Ms. Nielsen refused his request to have a court reporter record their interview, and instead pushed for one of her own staff members to take notes. Mr. Giorno then said Ms. Nielsen abruptly cancelled the interview.

“I find it appalling – appalling – that she is unwilling to take evidence accurately,” Mr. Giorno said in an interview.

“I want a formal record of what’s said between us. I don’t trust that what I say will be accurately recorded.”

Ms. Nielsen, however, said she invited Mr. Giorno to share any information he had on the matter and noted his participation is voluntary.

She said there is a process to ensure that witness statements are accurately documented.

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“If Mr. Giorno (or any other potential witness) is not comfortable participating in the review in accordance with the established process, he may submit any information he wishes me to consider in writing,” Ms. Nielsen said in an e-mail to The Globe.

“Mr. Giorno’s statement that I cancelled the interview because I do not ‘want an accurate record of what is said, just to rely on notes’ is misleading and incorrect.”

Conservative spokesman Cory Hann said the party chose Ms. Nielsen, a partner in a Toronto-based labour relations and employment law firm, because of her professional background in reviewing such matters.

“The review is being conducted independent of the party, and we have confidence in Ms. Nielsen’s ability to review the facts around the decisions made relating to Mr. Dykstra during the 2015 election campaign,” Mr. Hann said in an e-mail.

Conservative leader Andrew Scheer ordered the investigation in February as the party faced increasing pressure from within its own ranks to explain why Mr. Dykstra was allowed to run amid reports that he had been investigated by police after a sexual-assault allegation. Mr. Scheer has pledged to make the findings public.

Mr. Dykstra stepped down as president of the Ontario Progressive Conservatives in February, hours before Maclean’s magazine reported on accusations of sexual assault dating back to his time on Parliament Hill. The magazine also reported on high-level e-mails among Mr. Harper’s most powerful aides, who debated whether to remove Mr. Dykstra as a candidate in the 2015 election because of the allegations. Mr. Dykstra was allowed to run, but was defeated in his Southern Ontario riding.

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The other Conservative aides named in the e-mails included former campaign manager Jenni Byrne and senior campaign officials Ray Novak and Lynette Corbett. Ms. Byrne and Ms. Corbett did not respond to a request for comment on Friday.

Mr. Novak said he had nothing to add to the matter.

Mr. Giorno in February told The Globe the campaign never discussed the future of Mr. Dykstra’s candidacy, but later revised his comments to say he did not remember because he no longer had campaign e-mails. He maintained he was unaware of the specific allegations.