The Royal Canadian Mounted Police filed charges Thursday against former Senator Mike Duffy after a criminal investigation into his expense claims.
The Senate voted last fall to suspend him.
The probe started because of expense claims relating to Duffy's declared primary residence in Prince Edward Island and a secondary residence in Ottawa.
It broadened into an investigation of a $90,000 payment to Duffy from Nigel Wright, who served as Prime Minister Stephen Harper's former chief of staff. The payment allegedly was intended to help Duffy pay back the disputed housing claims and unrelated to official senate business.
But investigators also found evidence that payments Duffy took from consulting contracts circumvented senate rules.
The RCMP said it will bring 31 charges against Duffy, including multiple counts of fraud and breach of trust, plus bribery of a judicial officer and fraud on the government.
In October, the RCMP filed court documents seeking banking information for Gerald Donohue, a friend of Duffy's. The investigator alleged Donohue was paid $65,000 over four years by Duffy's senate office "for little or no apparent work."
Duffy is scheduled to appear in court in Ottawa on September 16.
Two other former senators -- Conservatives Patrick Brazeau and Pamela Wallin -- were suspended last November for similar questionable expense charges.
And Liberal Mac Harb resigned from the senate last summer after paying back $231,000 for ineligible housing and travel expenses.
Harb and Brazeau face criminal charges of fraud and breach of trust, CBC News said, while Wallin hasn't been charged.
Julie DiMauro is the executive editor of FCPA Blog and can be reached here.