Giuliano Zaccardelli is denying there was any political interference behind his decision to step down as head of the RCMP, saying he told the truth and that he leaves his post with a clear conscience.

The outgoing commissioner tendered his resignation Wednesday amid controversy over conflicting statements he made about events leading up to Maher Arar's deportation to Syria in 2002.

An emotional Zaccardelli told a news conference Thursday that he is resigning to maintain the confidence of Canadians in the RCMP. He said he admitted his mistake and chose to go public even though he knew the consequences.

"I had no choice; I had never had any choice but to tell the truth," said Zaccardelli.

"Far beyond any difficulty I might face individually as a result, it is the confidence of Canadians in the Royal Canadian Mounted Police that must be protected at all costs."

At issue was what Zaccardelli knew -- and when he knew it -- about Arar's deportation to Syria by U.S. authorities, who reportedly acted partly on the basis of information provided by the RCMP.

Zaccardelli told a parliamentary committee on Sept. 28 that he became aware shortly after Arar's deportation that the RCMP had incorrectly told the U.S. that Arar had ties to al Qaeda.

But Zaccardelli said this week that he didn't know the details until this fall.

He told reporters that he first found out about Arar in 2002, when Arar was deported to Syria.

"I was told certain things about him. I was told that he was a person of interest. I was told that we could not charge him. I was told we shared information with the Americans about him. I was told that we could not prevent him from coming back into Canada," he said.

It was only when he read Justice Dennis O'Connor's report on Arar in 2006 that he had "the complete picture" -- and he felt it was his duty to clarify his mistake by appearing before the commission this week.

"I knew there had been mistakes made, but that had not been given to me in 2002. So when the reports in the media state that I went back the other day and stated that I knew nothing then, ... that is not correct."

Day testifies

Earlier today, Public Safety Minister Stockwell Day faced tough questions from the public safety committee about when exactly he knew about Zaccardelli's conflicting testimony-- and why the RCMP boss wasn't fired sooner.

It has been reported that Day and other key cabinet ministers, behind closed doors, were pushing for Zaccardelli to be fired as early as several months ago -- but that Prime Minister Stephen Harper resisted the pressure.

Day refused to directly answer questions on the subject when confronted by Liberal MP Mark Holland, who cited the report and accused the minister and Harper of being disingenuous in their surprise yesterday over Zaccardelli's new testimony.

Holland asked Day: "Did you push the prime minister for the commissioner to be released or fired? Yes or no?"

Day suggested that Holland read the entire article, saying he makes "very clear" that any suggestion of pressure from the top is "utter fabrication."

Later during question period, Day questioned Holland's motivation in pursuing "these little notions" and "conspiracies."

"I wonder if it has anything to do with the fact ... that as soon as we got Justice O'Connor's report about the mess that this pervious government had handled, we accepted all 23 recommendations immediately while they did nothing," said Day.

Holland also brought up a Nov. 2 letter the committee and the parliamentary secretary received from Zaccardelli, in which the commissioner apparently explained that he will be making a "contradiction."

Holland said he raised questions immediately after reading the letter and called for the commissioner's resignation -- but the federal government refused to act.

"The reality is you knew, and you did nothing," Holland told Day. "You knew that you could have, at that stage in time before it reached this crescendo of anger toward this public outpouring of rage, that you could have acted at the moment, and did not."

Committee member Dave MacKenzie, a Tory MP and parliamentary secretary to Day, said Holland seems to be the only committee member who inferred from the letter that Zaccardelli would "totally change his story as he did this week."

"But having said that," MacKenzie asked Day, "if you had reacted to whatever Mr. Holland thinks was in the letter that no one else could find -- would you consider that to be political interference in telling the commissioner what he should have done as a result of that?"

Day strongly denied Holland's allegations that he interfered or exerted any political pressure on Zaccardelli. He also said he felt he was neither lied to nor misled by Zaccardelli over the Arar affair despite the commissioner's contradictory testimony a day earlier.

"Never once have I felt that the commissioner lied to me or tried deliberately in anyway to lead me astray." Day said

"There could be other reasons for the contradiction," he added, "and other reasons, as the commissioner has said, that finally resulted in his resignation."

Day told the committee the federal government must take responsibility for the actions of previous administrations in what he calls the "tragic case" of Arar.

But he didn't apologize for the wrongs suffered by the Ottawa-based engineer, who was tortured in Syrian into making false confessions of terrorist involvement.

He said compensation talks with Arar and his lawyers are progressing and follow-up investigations of "three individuals" involved in the fiasco are nearing completion.

Late Wednesday, the prime minister's office denied another account of two senior government officials saying that Harper had defended Zaccardelli for months in the face of criticism from his own ministers.

When asked who those two officials were, Day said he doesn't keep track of Zaccardelli's schedule. He said he couldn't provide the committee a list of government officials the commissioner has met with, saying it would be "political interference" if he were to do so.

With files from The Canadian Press