The federal ethics commissioner has suspended her examination of the $90,000 cheque written to Mike Duffy by the prime minister's top aide to cover illegal expenses claimed by the senator, because the RCMP has opened a criminal investigation.

Mary Dawson said Thursday that under law, since Stephen Harper's former chief of staff, Nigel Wright, is also being investigated for the same matter by the RCMP to determine whether he has committed an offence under an Act of Parliament, she must cease her examination into whether Wright was in a conflict of interest when he wrote the cheque.

The RCMP announced Thursday the force will investigate why Wright gave a personal cheque to Duffy so he could repay money owed to the Senate for improperly claimed living expenses. Wright has since resigned from his post with the PMO and Duffy has resigned from the Conservative caucus, and is now an Independent senator.

On May 15, the Prime Minister's Office announced that Wright had dipped into his own bank account because Duffy had said he was unable to pay the $90,000 debt himself.

Harper has insisted he knew nothing of the gift until that time.

On June 4, Senate ethics officer Lyse Ricard suspended her investigation into the cheque Duffy received, because at that point, although the RCMP hadn't announced a formal investigation, it was looking into the matter.

A statement from the RCMP said the force was continuing its investigation "to determine whether a criminal act has taken place. It must be meticulous and carefully consider and examine all information."

The Prime Minister's Office said Thursday it has not been approached by the RCMP. "We would provide any possible assistance if asked," said Harper's director of communications, Andrew MacDougall.

Investigation raised question period

News of the RCMP investigation came just before question period in the House of Commons.

NDP MP Megan Leslie tried to get more information on the cheque.

"The government has refused to come clean about the nature of this deal because they've claimed that both the Senate and the ethics office are investigating. But this is no longer the case. Now that we're dealing with a police investigation in the Prime Minister's Office, will they stop hiding, will they show us the cheque and tell Canadians what was the terms of the secret deal and who in the Prime Minister's Office was involved in this deal?"

Heritage Minister James Moore, subbing for the prime minister who is in Europe for the G8 as well as high-level meetings on trade, replied that the ethics commissioner is following the rules, and then demanded to know why NDP Leader Tom Mulcair wasn't in the House of Commons.

"We know he is on the Hill," said Moore, referring to Mulcair's run-in with the RCMP Thursday after he drove his car though a security checkpoint without stopping.

Liberal Leader Justin Trudeau then asked, "Can the minister of public safety confirm whether the RCMP's investigation into Nigel Wright falls under section 119 and 121 of the Criminal Code for bribery and frauds on the government?"

Moore replied that the RCMP is independent and does not answer to the government.

Opposition MPs have asked repeatedly to see a copy of the cheque Wright said he wrote to Duffy, but so far that has not happened.