Some of those same senators later worked in tandem with the Prime Minister's Office to make sure Mike Duffy was not publicly admonished for failing to grasp the rules around his own expenses.
Transcripts of police interviews with former Senate clerk Gary O'Brien and top Senate auditor Jill Anne Joseph were filed in court this week, in conjunction with Duffy's ongoing criminal trial.
They provide a new window into what was going on in the Senate backrooms at the height of the expense scandal.
Joseph was asked in early 2013 to review whether senators had pieces of government ID that proved they lived in the province they represent in the Senate. It had become a major issue in the news, with questions about how much time Duffy spent in Prince Edward Island.
"I did up my little report but they didn't like it, because I argued that there was a lack of clear criteria surrounding residency and they said, no no, no, it's very clear. Primary residence they're supposed to live there," she told the RCMP.
While the meaning of primary residence was perhaps clear, Joseph maintained the rules around how to prove it for finance purposes were not. That was later borne out when the Senate further tightened its rules, she added.
The issue grew so heated that Joseph told police she was eventually shut out of meetings, and that senators told the clerk her report was incompetent. The longtime employee said she considered quitting her post.
O'Brien also said that he felt the tension during that period in the spring of 2013, one that he described as the busiest of his career.
When doubts began to be raised about Duffy's expenses, O'Brien revealed that Liberal Sen. George Furey wanted the matter sent to police, but was ignored. The external firm Deloitte was looking into the claims.
"There was a feeling that perhaps there should again be a chance, you know, following our normal practice before we refer things to police, we do an internal investigation on the thing," O'Brien said.
He recounted how once Deloitte's report was filed, Conservative senators David Tkachuk and Carolyn Stewart Olsen unilaterally changed the Senate's report on Duffy's expenses. They did not consult Furey, who sat on the same subcommittee dealing with the issue.
Emails previously filed in court have shown how figures within the Prime Minister's Office, in conjunction with Tkachuk and Stewart Olsen, collaborated together on how to alter the committee report on Duffy.
In the end, it did not include the same critical language as the reports issued on former Liberal senator Mac Harb and Sen. Patrick Brazeau, a former Conservative.
O'Brien told police he thought it was inappropriate for the PMO to meddle in the issue.
"Yeah, I think the obligations of the Senate as the legislature would override the executive on this one," O'Brien said.
"Because this is an audit done, ordered by [the committee], you know?"
Joseph and O'Brien are expected to be called by the defence to testify at the Duffy trial.
Their police interviews have suddenly come up in the trial because of a dispute between the defence and the Senate over the release of Joseph's internal audit of senators' residency status.
The same secretive Senate internal economy committee that first tasked Joseph with conducting the internal audit is now claiming parliamentary privilege to prevent its release. Parliamentary privilege refers to certain protections and immunities enjoyed by parliamentarians.
That issue is expected to come up Friday before Justice Charles Vaillancourt.
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