OTTAWA - A look at key dates in the ongoing evolution of the Senate expenses scandal:
June 13, 2012: auditor general Michael Ferguson releases a study of Senate expense claims; in some cases Senate administration didn't have the right documents to support claims for travel and living expenses.
Nov. 21, 2012: Senate committee asked to examine housing allowance for Conservative Sen. Patrick Brazeau, who lists a home in Maniwaki, Que., as his primary residence despite appearing to live full-time within a 100-kilometre radius of Ottawa.
Dec. 3, 2012: Similar questions raised about Conservative Sen. Mike Duffy, who claims a primary residence in P.E.I. despite being a longtime Ottawa resident.
Dec. 4, 2012: Duffy says he got an email from Nigel Wright, the prime minister's chief of staff, saying it appeared that Duffy's residence expenses complied with the rules.
Dec. 6, 2012: The Senate widens its audit of housing expenses to include Liberal Sen. Mac Harb, who claims a home near Pembroke, Ont., as his primary residence, and begins examining residence claims of all senators, who are constitutionally bound to live in the provinces they represent.
Feb. 5: Reports emerge that Duffy applied for a P.E.I. health card in December 2012 and that he does not receive a resident tax credit for his home on the island.
Feb. 8: Senate hires external auditing firm to review Brazeau, Duffy and Harb's claims.
Feb. 11: According to Duffy, he meets Wright in the Langevin Block, which houses the Prime Minister's Office, to set up a meeting with Prime Minister Stephen Harper later in the week. "That's when I first heard about it and immediately voiced my objections to this fake pay-back scheme," Duffy says.
Feb. 13: The date Duffy says he meets Harper and Wright after a Conservative caucus meeting. Harper tells Duffy he must repay questioned housing expenses. "The prime minister agreed I had not broken the rules but insisted I pay the money back, money I didn't owe, because the Senate's rules are, in his words, 'inexplicable to our base,'" Duffy says.
Feb. 21: Duffy agrees to follow what he later describes as a PMO-drafted plan to cover up the source of the $90,000, including a story that he borrowed the money from RBC. "On Feb. 21, after all of the threats and intimidation, I reluctantly agreed to go along with this dirty scheme," he says.
Feb. 22: Claiming confusion with the rules, Duffy pledges to pay back the expenses. "My wife and I discussed it and we decided that in order to turn the page to put all of this behind us, we are going to voluntarily pay back my living expenses related to the house we have in Ottawa.''
Feb. 27: Prime Minister Stephen Harper says all senators meet the requirement that they live in the area they were appointed to represent.
Feb. 28: Senate audit fails to turn up any questionable housing allowance claims beyond those of Brazeau, Harb and Duffy.
Late February: Duffy says he was under increasing pressure to pay his expenses or be tossed from the Senate. "I said: 'I don't believe I owe anything, and besides which, I don't have $90,000.' 'Don't worry,' Nigel said, 'I'll write the cheque.'"
He also says a carefully drafted agreement was to protect him: "An undertaking was made by the PMO, with the agreement of the Senate leadership, that I would not be audited by Deloitte, that I'd be given a pass, and further, that if this phoney scheme ever became public, Sen. LeBreton — the leader of the government of the day — would whip the Conservative caucus to prevent my expulsion from the chamber."
Apr. 19: Duffy confirms he has repaid more than $90,000 in Senate housing expenses. "I have always said that I am a man of my word. In keeping with the commitment I made to Canadians, I can confirm that I repaid these expenses in March 2013.''
May 9: Senate releases report into housing claims, along with Deloitte audit. Deloitte says three senators live in Ottawa area, but that the rules and guidelines are unclear, making it difficult to say categorically that anyone broke the rules. Harb and Brazeau are ordered to repay $51,000 and $48,000, respectively. Harb says he will fight the decision.
May 10: Conservative House leader Peter Van Loan says of Duffy: "He showed the kind of leadership that we would like to see from Liberal Sen. Mac Harb, who instead is taking up arms against the Senate, saying that he should not have to pay back inappropriate funds.''
May 12: RCMP says it will examine Senate expense claims.
May 14: Brazeau says he also broke no rules and is exploring all options to overturn an order to pay the money back.
May 15: The Prime Minister's Office confirms that Wright personally footed the bill for Duffy's housing expenses because Duffy couldn't make a timely payment.
May 16: Duffy resigns from Conservative caucus.
May 17: Sen. Pamela Wallin also announces she's leaving the Conservative caucus. Her travel expenses, which totalled more than $321,000 since September 2010, have been the subject of an external audit since December.
May 19: Wright announces his resignation as the Harper's chief of staff, a move Harper says he accepts with "great regret." Wright is replaced in the chief of staff's role by Ray Novak, who has been by Harper's side since 2001. In October, Harper says Wright was "dismissed."
June 3: Sen. Marjory LeBreton, the Conservative leader in the Senate, says she intends to ask the auditor general to look into all the expenses of the upper chamber. LeBreton says she will introduce a motion calling for a comprehensive audit of expenses.
June 6: Conservative and Liberal senators agree to invite the auditor general to scrutinize the way they spend taxpayers' money. The same day, Harper tells the Commons that Wright paid the $90,000 with his own money: "Mr. Wright wrote a cheque on his own personal account and gave it to Mr. Duffy so he could repay his expenses. He told me about it on May 15. He obviously regrets that action. He has said it was an error in judgment and he will face the consequences as a consequence."
June 13: The RCMP confirms it has launched a formal investigation into the involvement of Nigel Wright in the Senate expense scandal. Brazeau and Harb are given 30 days to reimburse taxpayers for their disallowed living expenses — bills that together total more than $280,000.
July 4: Media reports say RCMP investigators allege that the Conservative party had planned to repay Duffy's improperly claimed living expenses, but balked when the bill turned out nearly three times higher than expected.
July 5: Harper is accused of misleading Canadians after repeatedly insisting Wright acted on his own when he gave Duffy $90,000 to reimburse his invalid expense claims. The RCMP says in a court document that Wright told three other senior people in the PMO about the transaction.
July 17: Harper's office says it has not been asked by the RCMP for an email at the heart of its criminal investigation into the Senate expenses scandal. The PMO denies withholding the email, which apparently summarizes the deal struck between Duffy and Wright to pay off invalid expense claims.
Aug. 13: The full extent of Wallin's questionable expenses are laid bare as the Senate releases a damning audit of her travel claims, calls in the Mounties and orders her to pay back tens of thousands of dollars.
Aug. 21: Wallin is informed she would have to reimburse the Senate a grand total of $138,970 for ineligible travel expense claims. Wallin was already on the hook for $121,348 after an independent audit of her travel expenses.
Aug. 26: Mac Harb, a veteran Liberal politician embroiled for months in a battle over his Senate expenses, resigns from the upper chamber. Harb, who earlier left the Liberal party to sit as an independent, drops a lawsuit and pledges to repay his questioned living and expense claims.
Aug. 27: Two Conservative senators deny allegations that they conspired to cover up the repayment of Duffy's expenses. David Tkachuk and Carolyn Stewart Olsen, who both sit on a committee reviewing improper expense claims by senators, were responding to a CTV report that said they pressed Duffy to accept a secret $90,000 cheque from Wright.
Sept. 6: Wallin is told she had until Sept. 16 to repay tens of thousands of dollars in ineligible travel expenses.
Sept. 13: Wallin pays back her dubious travel claims while accusing some fellow senators of succumbing to a "lynch mob'' mentality. The Saskatchewan senator says she has paid back $100,600, plus interest, on top of $38,000 already repaid.
Oct. 8: RCMP allege Duffy awarded $65,000 in Senate contracts to Gerald Donahue, a friend and former TV technician, who did little actual work for the money.
Oct. 17: Claude Carignan, the government's new leader in the Senate, introduces motions to suspend Duffy, Wallin and Brazeau from the Senate. The motions call for the three to be stripped of their pay, benefits and Senate resources.
Oct. 18: Wallin's lawyer, Terrence O'Sullivan, says his client is preparing to fight her suspension. O'Sullivan calls the gambit an "affront to Canadian democracy" designed to help the Conservatives change the channel.
Oct. 21: Duffy's lawyer, Donald Bayne, alleges Harper's staff and key Conservative senators behind a scheme to have Duffy take the fall for wrongdoing that they agreed he had not committed.
Oct. 22: In an explosive speech in the Senate chamber, Duffy accuses Harper's office of orchestrating a ''monstrous fraud'' aimed at snuffing out controversy over his expenses. Duffy accuses the prime minister of being more interested in appeasing his Conservative base than the truth.
Oct. 23: Wallin follows Duffy's lead with her own speech in the Senate, describing the suspension motion against her as "baseless and premature" and designed "to remove a perceived liability, namely me."
Oct. 25: Brazeau drops a bombshell of his own, saying Carignan earlier that same day took him aside and offered him "a backroom deal": apologize publicly for his actions in exchange for a lighter punishment. Carignan acknowledges the conversation but described the offer as one made out of "friendship."
Oct. 28: Duffy delivers again, this time saying the Conservative party made arrangements to cover his $13,560 legal bill. "The PMO — listen to this — had the Conservative party's lawyer, Arthur Hamilton, pay my legal fees," Duffy says. He also casts doubt on whether Wright actually paid the $90,000: "I have never seen a cheque from Nigel Wright."