Ferguson said his office hired an outside security firm to investigate his staff to see if any of them could have leaked the audit to journalists ahead of its public release in early June 2015.

OTTAWA — Auditor general Michael Ferguson says a leak of his high-profile review of Senate spending couldn't have come from his office, pointing the finger back at the Senate as the source of the unauthorized release.

Auditor General Michael Ferguson waits to appear at a Senate committee in Ottawa, Tuesday May 17, 2016. (Photo: Adrian Wyld/CP)

He told senators investigating the source of the leak that he is confident any information in the audit didn't come from his people, but said he can't be 100 per cent sure.

It was that possibility that senators on the Senate's rules committee locked on to as they used the morning meeting to blame Ferguson's office as the source of the leak.

This investigation is the second time in as many years that the Senate has looked into the leak of Ferguson's report, an event that senators argue violated their parliamentary privilege and the right to see the document before the public.

In some cases, senators said they learned the details of the audit from reading media reports.

Names of 9 senators made public

Leaks to multiple media outlets, including The Canadian Press, made public the names of nine senators who would be recommended for referral to the RCMP for a criminal review, the total amounts owing for the 30 senators identified in the report as having problematic expense claims and the recommendations Ferguson made to overhaul Senate spending rules.

"That was what was violated — that this was in the public domain before senators received it in the Senate," said Sen. Anne Cools.

"That was not violated by me or by my office," Ferguson responded. "We did not leak the report."

"I'm not saying that you did," Cools said.

Ferguson outlined how his office increased security around the Senate audit, including logging all staff accessing files, coding files with numbers instead of names and having motion detectors and alarms installed in the room holding audit documents.

Leak sparked 'wild, sensationalized speculation'

He said all of this was designed to maintain confidentiality on a report that his office knew had heightened political interest.

Ferguson says only 23 hard copies of the report were available ahead of its public release: 12 copies were delivered to the Senate on June 4, one day after 11 copies were made available to Ferguson's staff.

He said no copies or other information were provided to the Prime Minister's Office.

The only information Ferguson confirmed publicly before the report was released was the number of senators named in his report.

Ferguson said he did that during a CBC television interview because he wanted to set the record straight to end wild, sensationalized speculation.

He said it was a decision made on the spot during an interview.

"I felt it was the right decision to make," Ferguson said.

The leak of Ferguson's final report was the last in a series of disclosures during the two-year long audit that senators were told not to publicly discuss and for which they signed confidentiality agreements.

Senators ordered the audit in the summer of 2013 amid a spending scandal in the upper chamber that engulfed four of its members.

Since then, the Mounties have closed files on at least 24 of the 30 senators named in the report and an independent arbitrator slashed repayment bills for 10 of 14 senators who challenged Ferguson's findings.

The Senate has vowed to take seven former senators to court over their refusal to pay almost $528,000 in improper expense claims outlined in the auditor general’s June 2015 report.

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