The RCMP is treating Sen. Mike Duffy’s improper expense claims as an alleged breach of trust, and has widened its investigation into the Senate expense scandal to include Senators Mac Harb and Patrick Brazeau, court documents show.

Documents released Thursday also show the RCMP obtained campaign records for 12 Conservative candidates as part of a criminal investigation into Duffy, code-named Project Amble, CTV’s Ottawa Bureau Chief Robert Fife reported.

“It’s very clear that laws have been broken and the RCMP is now investigating these Conservative and Liberal senators.” NDP MP Peter Julian told CTV News. “I’m glad in a sense the RCMP is involved, but I also think it's a sad day for Canada when Canadians have to see this kind of activity in the Senate.”

Documents filed in an Ottawa court show that police investigators collected certified copies of electoral campaign returns for 12 Conservative candidates, “specifically expense claims and payment documents related to Mike Duffy.”

The list of candidates includes Natural Resources Minister Joe Oliver and Conservative MPs Gerald Keddy, Greg Kerr, John Carmichael, Robert Goguen, Tilly O’Neill Gordon, Rodney Weston, Scott Armstrong and Lizon Wladyslaw.

Duffy billed both the Senate and the Conservative Party on the days that he campaigned for the Tory candidates.

A DVD containing copies of Duffy’s residence declarations, expense and travel claims were also seized, according to the court documents.

The documents show that the RCMP’s Sensitive and International Investigations detachment is leading the probe.

The RCMP is also examining property records linked to Harb.

Court documents show the RCMP obtained land records for a home in Cobden, Ont., that previously belonged to Harb.

Both Duffy and Harb were found to have improperly claimed living expenses when the Senate ordered external audits. Both have since stepped away from their respective caucuses.

Harb has been ordered to repay $231,649 in improper expense claims that date back to 2005.

He has launched a legal challenge against repaying that money.

"This is Canada. We have a justice system. A right to go through the process and in the end justice will be served," Harb said in a statement.

Duffy paid back the $90,172 he owed before the audit was released, but it was later revealed that he received a cheque for the repayment from Prime Minister Stephen Harper’s then chief of staff, Nigel Wright.

The RCMP is investigating Wright’s cheque to Duffy. No criminal charges have been laid and Harper has said that he didn’t know anything about the transaction.

Sen. Patrick Brazeau, who was kicked out of the Conservative caucus on a different matter, is also fighting a similar order in the wake of the expense audits.

Brazeau was found to have improperly billed taxpayers for $51,000.

The RCMP would not say if Harb and Brazeau are under criminal investigation.

Senate ethics officer asked to probe Boisvenu 

The Senate ethics officer was asked Thursday to investigate an alleged attempt by Conservative Sen. Pierre-Hugues Boisvenu to arrange a Senate job and extra holiday time for a former office assistant he was in a relationship with.

Liberal Sen. Celine Hervieux Payette alleged Boisvenu ignored the ethics commissioner's order to end his relationship with Isabelle Lapointe.

“The law and order guy is treating the Senate as if it was a small family enterprise that you can hire everyone around you,” she told Power Play.

NDP Leader Thomas Mulcair said the Senate scandals point to the need to abolish the upper chamber.

He told Power Play on Thursday that he believes the vast majority of Canadians feel the same way.

“Support of abolition, pure and simple, is at 90 per cent in Canada right now,” he said. “We want Canadians to understand that this is going to be on the table when we form the government in 2015.”