OTTAWA -- A senior Conservative senator who was labelled as the guru of Senate rules by Mike Duffy's judge says the widely held view of his role in the whole affair is more fiction than fact.

As Duffy resumed his seat in the upper chamber on Tuesday, Sen. David Tkachuk insisted he never advised him on questions about housing and travel allowances, despite Duffy's criminal trial having been told otherwise.

Tkachuk said the only advice he gave during a January 2009 meeting of new senators was about caucus responsibilities, since he hadn't yet been appointed to the executive of the Senate's internal economy committee, which oversees expense rules.

Duffy testified at his trial that he spoke with Tkachuk one-on-one after the meeting and asked whether he could or should claim expense against his Ottawa-area home as a secondary residence.

The question came amid media reports that raised questions about Duffy's constitutional eligibility to sit as a senator from Prince Edward Island.

Duffy testified Tkachuk told him the claims were essential to quell eligibility questions and that Duffy should claim for daily meal allowances in the capital, even though Duffy said he personally didn't believe in them.

Tkachuk said the meeting never happened.

In an interview with The Canadian Press, Tkachuk said he would have told Duffy to speak with Senate lawyers or someone on the internal economy committee if he faced questions on Jan. 7, 2009, about Senate rules. Tkachuk said he didn't join the internal economy committee until Feb. 10, 2009.

"It's important that people know I wasn't sitting there advising Sen. Duffy about how he should conduct his residency claims at a meeting that I never had with him and that I had no right to be at because I wasn't a member of internal economy," Tkachuk said.

Duffy has not responded to a request for comment. He left the Senate Tuesday without saying a word to reporters.

Late last month, Ontario Court Justice Charles Vaillancourt dismissed 31 criminal charges of fraud, breach of trust and bribery against Duffy, all them related to his Senate expenses. Vaillancourt called the Senate rules vague and ruled that Duffy was forced to take a $90,000 payment from Nigel Wright, Stephen Harper's then chief of staff, to pay off his politically problematic housing expenses even though Duffy contended he had done nothing wrong.

Tkachuk's role in the affair related to his position on the internal economy committee, which oversaw the audit of Duffy's expenses and subsequent changes to spending rules and his move to end the audit after the repayment of Duffy's housing claims.

Tkachuk wasn't called to testify and he says the Crown never contacted him, even though he was available to take the stand. He said he was surprised he wasn't called as a witness.

He said the facts in the criminal trial skewed his role in the matter and he wants to tell his side of the story.

"I know what the truth is, as far as I'm concerned, and the facts bear me out," he said.

Duffy returned to Parliament Hill on Monday for the first time since his acquittal and he took his seat Tuesday among the colleagues who voted to suspend him without pay in late 2013.

The main debate of the day was about whether the appointment of two partisans-turned-independent senators -- former Conservative Diane Bellemare and former Liberal Grant Mitchell -- as assistants to Peter Harder, the government leader in the Senate, violated rules and the laws governing Parliament.

Duffy sits near the front door, in the back row close to Patrick Brazeau and Pamela Wallin, former Conservatives who were also suspended without pay over questionable expenses.

Duffy still has supporters.

Sen. John Wallace said the suspension process was a debacle and a breach of due process.

He said the Senate should give Duffy back the almost $270,000 in salary he lost during his suspension.

"There was a rush to judgment and some would say a rush to political judgment and he paid the price for it," Wallace said.

To get the money back would require passing a motion, which any senator could put forward.

Sen. Don Plett, the Conservative whip, wouldn't say whether Duffy deserved the back pay.

"His pay was not deducted because of any criminal charges. They were deducted because of a disciplinary action, well before there were any criminal charges. The two are not related," Plett said on his way into the Senate chamber.