The RCMP may have dropped its criminal investigations into nine senators named in last year’s auditor general’s report, but that doesn’t mean the Senate will stop trying to recover expenses.

CTV News has learned the Senate will, starting next week, send letters to retired senators demanding payment of disallowed expenses and start docking the paycheques of sitting senators who don’t pay up.

Judge Ian Binnie is expected to say Monday how much he believes the 14 senators who agreed to binding arbitration still owe.

Some of the 30 senators named in Auditor General Michael Ferguson’s audit have already paid what Ferguson said they owed.

Seven senators have neither repaid nor participated in arbitration.

Former House of Commons Law Clerk Rob Walsh said he expects the Senate will hire lawyers to go after those who refuse to pay, “and suffer the legal costs.”

Ferguson determined in his report last June that the 30 senators in question owed a combined $991,917.

Considering that the audit alone cost $24-million, and that countless taxpayer dollars have been sunk into investigations that led to no charges, some are asking whether the costs are justified.

Prime Minister Justin Trudeau said Wednesday that he doesn’t believe the expenses are a waste of money.

Speaking to reporters at the United Nations in New York on Wednesday, Trudeau said the Senate audits and police investigations “highlighted the need for greater transparency, greater openness, greater accountability and indeed, a distancing from partisanship and the patronage that has defined the Senate over recent years and indeed, decades.”

The Globe and Mail reported on Tuesday that RCMP investigators have exonerated 24 of 30 senators whose expense claims were flagged by the auditor general. The Mounties are also expected to clear the remaining six senators of any wrongdoing, the Globe reported.

The audit flagged questionable expense claims filed by 30 senators and the Senate later decided to refer nine cases to the RCMP.

According to the Globe report, the RCMP eventually decided to review all 30 cases and found that most of them did not warrant a formal investigation.

The auditor general’s audit called for “transformational change” in the Senate, and highlighted many issues with the way senators’ expenses are claimed, reviewed and controlled. 

Trudeau said Wednesday that his government is committed to “an Upper House that actually examines in a responsible and much less partisan way.”

“We’ve seen from the Supreme Court that it is not in the cards for us to simply wish the Senate away, and therefore the Liberal government has undertaken to make significant steps to improve … its function and to restore its place of confidence in the minds of Canadians who observe our Parliament,” he said.

The trial of Sen. Mike Duffy, whose expense claims did lead to 31 criminal charges, wrapped up last month and a verdict is expected in April. Duffy has repeatedly denied any wrongdoing.

With a report from CTV National News Senior Political Correspondent Glen McGregor