The Prime Minister's Office played a key role in changing the findings of a 2013 audit into Mike Duffy's living expenses, as part of a strategy to keep the now-suspended senator quiet as the PMO tried to find a solution to questions over the controversial claims, RCMP officers allege in new court documents.

The Senate administration had hired the auditing firm Deloitte to look into the expense claims of senators Patrick Brazeau and Mac Harb, as well as those of Mr. Duffy. But the PMO and senior Conservative officials defended Mr. Duffy in the early stages of the controversy, in order to keep him quiet.

"A purpose of this is to put Mike in a different bucket and to prevent him from going squirrely in a bunch of weekend panel shows," former PMO chief of staff Nigel Wright said in an e-mail to colleagues on Feb. 7, 2013.

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Mr. Wright's e-mail, which went to PMO colleagues Chris Woodcock, Ray Novak, Andrew MacDougall and Joanne McNamara, added: "Mike is very pleased with this so it will give us a little bit of time if [Conservative senator David Tkachuk] can pull it off."

In an e-mail on the same day, Chris Montgomery, a staffer in Conservative senator Marjory LeBreton's office, told Mr. Wright a plan to get outside legal advice on Mr. Duffy's residency issues was designed to "protect senator Duffy."

The newly released documents reinforce the notion the PMO and the Conservative Party initially went to great lengths to contain the political damage flowing from expenses claimed by Mr. Duffy after his 2008 appointment to the Senate.

A long-time resident of Ottawa, Mr. Duffy declared his primary residence was his PEI cottage, which allowed him to claim expenses for being on "travel status" when he worked in the Senate. Faced with a public furore, he said on February 22, 2013, that he would reimburse the expenses.

However, Mr. Duffy became persona non grata in Conservative circles when it was learned that Mr. Wright had ultimately paid back the controversial expenses, totalling $90,000, on his behalf.

The new documents into the matter were filed in an Ottawa court by the lawyer for Mr. Duffy, the former broadcaster who is currently on trial on 31 charges of fraud, breach of trust and bribery. Defence lawyer Donald Bayne recently filed a motion to obtain a series of reports and documents from the Senate, which is invoking parliamentary privilege to prevent their release.

Mr. Bayne's motion includes transcripts of two previously unreleased interviews by the RCMP with Gary O'Brien, the former Senate clerk, and Jill Anne Joseph, the Senate director of internal audit. The interviews were conducted by RCMP officers Greg Horton and Benoit Jolette.

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According to the RCMP, a number of Conservative senators and PMO officials secretly discussed the confidential Deloitte audit when it was nearing completion on May 7, 2013. The following day, Mr. Tkachuk and his Conservative colleague, Carolyn Stewart Olsen, managed to delete key passages of the report by bypassing the normal Senate committee process.

"The report, we've learned through the investigation, had made its ways to the PMO, to their office, and, I guess, revisions, what they wanted to have written in the report, was done," Corporal Jolette told Mr. O'Brien during their interview. "Throughout our investigation, like I said, we've learned that PMO has had a lot of communication with the diverse senators who were involved in these committees and sub-committees."

Mr. O'Brien confirmed that he received a visit at his offices on May 8 from Mr. Tkachuk, before a Senate sub-committee held a formal discussion on the Deloitte audit.

"Senator Tkachuk came in here after 4 [p.m.], he wanted to look at this and he reviewed it and he said, 'Carolyn and I would like two more changes,'" Mr. O'Brien told the RCMP.

Mr. O'Brien said the portions of the report that were deleted referred to Mr. Duffy's travels between Ottawa and PEI and his "continued presence in Ottawa," which raised questions about the legitimacy of his expense claims.

"That was a confidential report, I'm surprised it was shared so widely," Mr. O'Brien added about the PMO's involvement in the matter.

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Ms. Joseph told the RCMP she was surprised to discover that key findings of the report were amended without her knowledge or that of Liberal senator George Furey, who was also part of the sub-committee. "I just found that odd, that it would take place outside of the normal process," she said.

She was particularly displeased by the role played by Ms. Stewart Olsen in the matter.

"Here she was a member of the audit subcommittee, but her objective was not to get to the truth of the matters and deal with them the way I wanted to deal with them," Ms. Joseph said. "Her consideration seemed to be more like, what's the media going to do with this information?"

Efforts to obtain comment from Ms. Stewart Olsen, Mr. Tkachuk and the PMO were unsuccessful. Mr. Wright's lawyer has said his client will not comment until he testifies at Mr. Duffy's trial.