The RCMP investigation into the expense claims of at least two senators is code-named Project Amble, CBC News has learned.

Court records detailing the initial stages of the probe show the force has gathered documents related to the expense claims of senators Mike Duffy and Mac Harb.

Court records released Thursday show the RCMP's sensitive and international investigations division seized records on June 5 and June 13 from Elections Canada's files for 12 Conservative MPs for whom Duffy campaigned during the 2011 federal election. The records were handed over without a warrant.

Under the heading "Nature of event" on the exhibit report filed for some of Duffy's records, Const. Jane Lee typed "Breach of trust."

The records show the Mounties confirmed Harb owned a home in Cobden, Ont., until May 2011.

Harb has filed a lawsuit against the Senate over how it handled the expenses controversy. He says he broke no rules and that Senate administration approved his expense claims.

Harb has not been contacted by the RCMP.

Duffy, Harb and Senator Patrick Brazeau were audited over claiming a housing allowance intended for senators who had to maintain a second residence in the National Capital Region. All three had previously worked in the Ottawa area but started claiming the secondary residence allowance after they were appointed to the Senate.

Senate gave records to RCMP

Senator Mike Duffy, left, appears at a campaign event for Mississauga, Ont. Conservative candidate Wladyslaw Lizon during the 2011 federal election. (Facebook)

Records obtained by CBC News show Duffy also claimed Senate per diems when he was campaigning for Conservative candidates in the 2011 federal election campaign.

The list of candidate files retrieved from Elections Canada seems to match the list of appearances Duffy made with candidates in Atlantic Canada, the Greater Toronto Area and the Northwest Territories:

Scott Armstrong.

John Carmichael.

Robert Goguen.

Gerald Keddy.

Greg Kerr.

Sandy Lee.

Wladyslaw Lizon.

David Morse.

Joe Oliver.

Tilly O'Neil Gordon.

Gin Siow.

Rodney Weston.

The RCMP also got records from the Senate, including two DVDs with Duffy's expense claims and the minutes from the internal economy committee meeting of May 28. The expense claims go back to January 2009, the month Duffy started his Senate posting and more than two years further back than an audit by accounting firm Deloitte.

Duffy had said he paid back the Senate for $90,000 in expenses he claimed that were not appropriate, but Prime Minister Stephen Harper's former chief of staff, Nigel Wright, later said that he had given Duffy the money to make the payment. Duffy stopped co-operating with the Deloitte audit once that payment was made.

The first confirmation that the RCMP was looking into spending by Duffy, Harb and Brazeau came on May 24 when Senate Speaker Noël Kinsella tabled a letter from the police force saying it wanted copies of Senate policies.

The letter, dated May 16, said the RCMP wanted the policies "in order to make a determination as to whether there are grounds to commence a criminal investigation."

Supt. Biage Carrese, of the sensitive and international investigations unit of the RCMP's national division in Ottawa, wrote that the RCMP is "conducting a review" of the Deloitte audits. He requested copies of guidelines over the last 10 years related to travel and living expenses and other administrative rules. The RCMP also wanted the Senate calendars for the last decade to determine when the upper chamber was sitting.

Kinsella said the information had been passed on to the RCMP.

The government was asked in question period on May 24 if Harper's office had been approached by the RCMP and Heritage Minister James Moore responded that it had not.