The RCMP has begun interviews with senators about Pamela Wallin's expense claims, widening an investigation launched earlier this year.
Ms. Wallin was ordered to repay more than $100,000 in questionable claims and about $14,000 in interest last month after an independent audit found she had billed the Red Chamber for expenses that were not related to her work as a senator.
She repaid the money in mid-September, but has maintained in her public statements that she was treated unfairly by the auditors and the Senate committee that ordered the review.
Senator Marjory LeBreton, who stepped down from her position as the government leader in the Senate earlier this year, confirmed that she was interviewed by the RCMP about Ms. Wallin's expense claims earlier this month.
Ms. Wallin is the fourth senator to come under scrutiny by police during the past year. Senators Mike Duffy, Patrick Brazeau and Mac Harb are also under investigation by the RCMP.
The Senate's internal economy committee, which requested the audit into Ms. Wallin's expenses, referred the matter to police last month after receiving the auditor's report.
The audit, conducted by Deloitte, listed dozens of claims Ms. Wallin made for trips auditors said were related to partisan or personal events. They also pointed out that the Senator's Microsoft Outlook calendar appeared "inconsistent" with previously archived versions, with meetings added, changed or deleted.
Earlier this month, Ms. Wallin said she would welcome an "independent and objective review" by police and would co-operate fully with any investigation. "I have not done anything wrong. I am not guilty of any misconduct," she wrote in the statement.
A former broadcast journalist who was appointed to the Senate by Prime Minister Stephen Harper, Ms. Wallin resigned from the Conservative caucus in May.