Mark Grenon will testify for a third day in a voir dire — a sort of trial within a trial to determine admissibility of evidence. Duffy's judge-only trial, which began April 7 in the Ontario Court of Justice, is in its 36th day.
Following the voir dire, Judge Charles Vaillancourt will determine how much, if any, of the testimony will be admissible.
Duffy has pleaded not guilty to 31 charges of fraud, breach of trust and bribery related to expenses he claimed as a senator and later repaid with money from the prime minister's then chief of staff, Nigel Wright.
Grenon traced the path of $90,000 of funds from Wright's account to an Ottawa-based law firm, into the bank account of Duffy, and finally to the receiver general of Canada.
Wright, who is expected to be called as a key witness when the third phase of the trial begins in August, was dismissed as chief of staff after the arrangement between Wright and Duffy was made public.
On Wednesday, during cross-examination, Grenon agreed with Duffy lawyer Donald Bayne that all the transactions made it appear as if Wright's $90,172.24, which was used to pay back the government, actually came from Duffy.
Bayne suggested Wright was trying to "baffle the receiver general and most of the Canadian voting public into thinking Mike Duffy has admitted a mistake and he's paid back $90,000."
But Grenon said it didn't look like these transactions were done with the intent to hide, because if concealment was the purpose, the transactions should have been layered.