One of the key witnesses at Mike Duffy’s trial is expected to testify this week that he was paid about $20,000 to act as a middleman and disburse money to the now-suspended senator’s personal trainer, makeup artist and others, CTV News has learned.

In previously released court documents, RCMP investigators have alleged that Duffy paid his friend Gerald Donohue $65,000 under a Senate-funded contract to carry out work that was “of little or no value.”

Donohue, a former TV executive who is not facing any charges, will take the stand this week as a Crown witness. He will be questioned about $65,000 worth of Senate contracts for consulting work that investigators allege he never performed. Of particular concern to the prosecutors is what Donohue knows about $25,000 that is still unaccounted for.

Early in the investigation, Donohue told the RCMP that he didn’t receive any money and admitted that he produced “no tangible work product for Duffy.”

But sources tell CTV’s Ottawa Bureau Chief Robert Fife that Donohue’s story has now changed. When he takes the stand, he is expected to admit that he was paid about $20,000 to act as a middleman and facilitate payments to others.

Those payments allegedly include $10,000 to Duffy’s personal trainer Mike Croskery, and thousands of dollars more to several people, including Conservative pundit Ezra Levant and former Tory staffer Bill Rogers, for political speeches and advice.

A makeup artist also allegedly received money. All of them have been subpoenaed.

Donohue’s contract was paid for out of the general expenses portion of Duffy’s Senate office budget.

Duffy faces 31 charges, including fraud, breach of trust and bribery, in relation to his living and travel expenses.

The bribery charge is related to a $90,000 personal cheque Duffy received from Prime Minister Stephen Harper’s former chief of staff, Nigel Wright. Wright secretly wrote the cheque to cover Duffy’s disputed expense claims.

Wright has not been charged by the RCMP in connection with the cheque.

The Mounties also allege that Duffy filed $50,000 worth of travel expenses as Senate business that were actually related to personal or partisan business. Among the allegedly improper expenses was a trip to Peterborough, Ont., to pick up a dog.

Duffy is represented by a high-profile criminal lawyer, Donald Bayne, who said that his client sees the trial as “his opportunity to clear his name” and show that he hasn’t done anything wrong.

With a report from CTV’s Ottawa Bureau Chief Robert Fife