When members of the Senate voted to invite the federal auditor general to audit their expenses, some senators may not have anticipated what they were letting themselves in for.

Most senators, lulled by an "honour system" in filling out expense forms could not have foreseen an audit that would be police-like in its scope. Nor could they have imagined that every claim and receipt would be scrutinized, and their names made public once the audit is complete.

The honour system, which was eliminated by the Senate this year, allowed two words — "Senate business"— to explain any trips they took, and didn't require receipts for airport taxis.

Auditor General Michael Ferguson seems to be aiming for the kind of sweeping investigative audits that occurred in Newfoundland and Labrador in 2007 and Nova Scotia in 2009. Those audits led to some members of each province's legislatures being charged and even going to jail.

Several senators, listening to Ferguson's plans during two meetings held in the aboriginal room of the House of Commons, asked if he is doing a forensic audit, and not the gentle probe they perhaps expected. Another senator said there was "a great deal of paranoia" expressed.

Ferguson's audit might go as far as doing physical inspections of the Ottawa-area houses or apartments many senators claim as secondary residences. As well, Ferguson's staff may visit the homes senators designate as primary residences in the provinces they were appointed to represent.

May interview neighbours

Few senators wanted to speak on the record, but some have said that Ferguson reserves the right to interview neighbours or people in the area of the senators' residences to see if they really live in what they call their primary residences, or, if some have moved full-time to their Senate-expensed secondary residences.

Under Senate rules, senators who live more than 100 kilometres from Parliament Hill can charge up to $22,000 a year for secondary housing expenses if they rent or own a property in or near Ottawa.

In Nova Scotia, provincial Auditor General Jacques Lapointe used similar powers when he and his staff entered MLAs' offices and demanded to see the flat screen TVs or generators they'd charged as expenses. Lapointe told CBC News he has subpoena powers, and Ferguson's office has confirmed that he does too.

Liberal Senator David Smith, asked Jan. 3 by host Terry Milewski on CBC News Network's Power & Politics if the audit would involve interviewing neighbours, answered, "It probably will."

Secrecy surrounds audit

A cloak of secrecy surrounds the audit. Letters sent to each senator about the audit are numbered, and must be mailed back to the auditor general's office.

Enclosed with a cover letter is a suggested draft consent letter which Ferguson asked senators to prepare on their own letterhead, sign and return. One senator said she'd heard 20 to 30 senators had not yet complied. There are 105 Senate seats.

In an email to CBC News, a spokesperson for the auditor general's office said, "These documents are printed on special paper bearing a mention that clearly forbids the reproduction and distribution of said documents."

One of the reasons Ferguson has so much leeway is because of the wide-open motion in the Senate in August inviting him in.

The motion was presented to senators while they were reeling from the scandal caused by the inappropriate expense filings of senators Mike Duffy, Pamela Wallin, Patrick Brazeau and the now-retired Mac Harb.

Duffy, Brazeau and Wallin were suspended without pay in November, and all four are being investigated by the RCMP.

The motion, moved by former government Senate leader Marjory LeBreton, reads, "That the Senate invite the auditor general of Canada to conduct a comprehensive audit of Senate expenses, including senators' expenses."

In a speech in the chamber, Independent Senator Anne Cools wondered whether LeBreton had even consulted her own Conservative caucus about the wording of the motion. "The motion before us is so open one could drive 25 tractor-trailers through it," Cools said.

Asked in an email about the wording of the motion, LeBreton said, "I will not comment on who I consulted."

LeBreton added that she'd like it acknowledged it was the "Conservative side" that brought on the most extensive examination of senators' expenses in Senate history.

"When we reached majority status," she wrote, "we initiated the practice of Senators' expenses being publicly reported ... This action exposed some very serious flaws not only in the way senators claimed expenses but also in the Senate's administrative oversight which was sorely lacking!"

LeBreton concluded, "More has been done to make the Senate accountable in the last three years than had been done in the previous 144 years!"

Speculation is that Ferguson's audit will be finished by December. Whatever revelations it offers could be fodder for the next general election, scheduled to be held in 2015.