OTTAWA -- After months of back and forth and uncertainty about his political future, Liberal MP Nicola Di Iorio has officially resigned as a member of Parliament.

House of Commons Speaker Geoff Regan announced the vacancy in his seat just before question period on Tuesday, saying that the Quebec MP informed him earlier in the day.

This comes after Di Iorio appeared in the House Tuesday morning to deliver a winding speech that puzzled some on the Hill, because it was thought he might be announcing his departure, but he did not officially inside the chamber.

Instead his remarks were in defence of his character, focusing on the NDP's call for a parliamentary investigation into his delayed resignation. Reached by CTV News for comment earlier Tuesday, Di Iorio deferred to his comments in the House.

Di Iorio vowed to resign as of Jan. 22 or when the House sitting resumed, which was yesterday, Jan. 28. The self-declared deadline came after many months of absence from the Commons and previously stated intentions to step aside.

The outgoing Liberal MP first announced in the spring of 2018 that he would be leaving politics, citing family reasons, but never resigned his seat. He then said this past fall that he was taking time to contemplate his political future. As he was mulling his political career, Di Iorio hadn't been seen in his seat in the House of Commons, but he had been seen working in his capacity as a lawyer.

Di Iorio has previously stated that Prime Minister Justin Trudeau approved his absence from the Hill to work on projects in his Saint-Leonard-Saint-Michel, Que. riding.

Asked about his departure, Liberal Whip Mark Holland said he wishes Di Iorio “all the best,” and denied that he was pushed out of caucus, saying it was his decision alone to leave.

NDP MP Nathan Cullen had raised the matter of Di Iorio's delayed departure in November, and again in December, arguing first that his explanation for not being in the House of Commons isn't "suitable" and his absence was infringing his constituents' rights to representation in Ottawa, and then that he was misleading Parliament about whether or not he was receiving his salary.

Defending himself on Tuesday, Di Iorio noted that neither the Speaker nor ethics commissioner had found a breach of the rules, and raised possible issues with translation of his past remarks. He says the NDP attempt to raise the issue was aimed at tarnishing his reputation.

On Tuesday, Regan said that there was not enough evidence to conclude that Di Iorio mislead the House, but implored all members to choose their words carefully when speaking in the Commons.

Speaking about his departure, Cullen said he wishes Di Iorio "health in his future" and suggested Parliament should have more powers to remove MPs in situations like this.

"When somebody simply isn’t showing up for work… There should be some consequence like there is in any other workplace," Cullen said.

During his remarks, Di Iorio did acknowledge his earlier stated intention to step down, but only in passing. He also made other claims that CTV News has not yet been able to verify, including that he did not receive a salary for the time he was not in the House; and that he made a $100,000 donation to an unnamed impaired driving charity during this time.

MPs receive a $172,000 salary, but after being absent for 21 days, they can have $120 a day clawed back each day going forward.

When MPs vacate their seat, they can either announce their intention to resign on the floor of the Commons, or deliver a written letter declaring their departure. At this point the Speaker can inform the Chief Electoral Officer of the vacancy to open up the potential for a byelection.

Trudeau has faced questions over his MP's exit plan. Asked to comment on the vacancy on his way in to question period, the prime minister said he will continue to make sure his party has "great MPs" representing communities across Canada.

However, in this case, Di Iorio's riding will remain without representation until the general election because the window of time in which a vacancy can be filled has closed. Part of the recently passed election reform bill, C-76, changes the rules to state that a byelection cannot be called within nine months of the scheduled general election date, which is October 21, 2019.

With files from CTV News' Michel Boyer