OTTAWA, Ontario -- Canadian police released surveillance video Thursday of the gunman accused of fatally shooting a soldier at a war memorial in Ottawa and said the suspect had recently applied for a passport and was "hoping to leave for Syria."

Royal Canadian Mounted Police commissioner Bob Paulson also says authorities had not been watching the gunman in the weeks before the deadly attack on a soldier at a war memorial on Ottawa on Wednesday.

Michael Joseph Zehaf-Bibeau, a 32-year-old petty criminal, then stormed the nearby Parliament building, where he was shot to death.

Surveillance video of the gunman accused of fatally shooting a soldier in Ottawa. CBS

Paulson said Thursday that Zehaf-Bibeau had recently applied for a passport, and authorities now believe he intended to go to Syria.

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"The passport was part of his motivation. His application was not rejected. His passport was not revoked," Paulson said. "He was waiting to get it and there was an investigation going on to determine to see whether he would get a passport."

Paulson said that the suspect's mother told them about her son's desire to go to Syria.

Police said they have found no connection between the two attacks on soldiers this week.

Law enforcement and U.S. government sources told CBS News the suspect was born in Quebec in 1982. He is from British Columbia and recently converted to Islam. Sources said he had a history of drug addiction prior to his conversion.

A U.S. law enforcement official told CBS News that the Canadian government was investigating whether the suspect was in contact with known militants in Syria -- possibly the Islamic State of Iraq and Syria (ISIS).

A law enforcement source also told CBS News senior investigative producer Pat Milton that Zehaf-Bibeau traveled to the U.S. at least four times, including twice last year. The source said that he visited the U.S. in May and November of 2013 and also once in 2012. He crossed into Minnesota by car in each of those trips, but the source had no information on his travels once inside the U.S.

Zehaf-Bibeau also flew from Vancouver to Las Vegas in 2010. He was apparently accompanied by other people on each of his four trips.

The suspect's mother said Thursday that she is crying for the victims of the shooting rampage, not her son.

In a brief and tear-filled telephone interview with The Associated Press, Susan Bibeau said she did not know what to say to those hurt in what authorities are calling a terrorist attack by a recent convert to Islam.

"Can you ever explain something like this?" she said. "We are sorry."

In a separate email to the AP expressing horror and sadness at what happened, Bideau said that her son seemed lost and "did not fit in," and that she hadn't seen him for more than five years before they spoke over lunch last week. "So I have very little insight to offer," she said.

Authorities said he killed a soldier standing guard at Canada's tomb of the unknown Wednesday, then stormed the nearby Parliament building, where he was shot to death.

It was Canada's second deadly attack in three days by a recent convert to Islam, and raised fears that the country is suffering reprisals for joining the U.S.-led air campaign against Islamic extremists in Iraq and Syria.

Prime Minister Stephen Harper linked both episodes to the "savagery" of radical ideologies abroad.

After initially reporting that two or three assailants may have taken part in the shooting rampage, Canadian police conceded Thursday that Zehaf-Bibeau was the lone gunman.

His mother, who has homes in Montreal and Ottawa, said she was devastated for the victims of the attack.

"If I'm crying, it's for the people," she said, struggling to hold back tears. "Not for my son."

Government officials credited 58-year-old Parliament sergeant-at-arms Kevin Vickers with shooting the attacker just outside the MPs' caucus rooms.

Vickers, a former Royal Canadian Mounted Police officer, serves a largely ceremonial role at the House of Commons, carrying a mace and wearing rich green robes, white gloves and a tall imperial hat.

Members of Parliament gave him a rousing standing ovation Thursday morning for saving their lives. As Vickers walked into the House of Commons, his lips quivered in emotion, and he acknowledged the applause by nodding solemnly.

Vickers said in a statement that he was "very touched" by the attention but that he has the close support of a remarkable security team.

In an uncharacteristically personal speech, Harper urged members of Parliament to seek medical help if they are suffering stress from the attack.

"Here we are in our seats, in our chamber in the very heart of our democracy, at work" Harper said. "We will not be intimidated."

Harper noted that both of this week's terror attacks in Canada came from citizens born in Canada.

On Monday, a man Harper described as an "ISIL-inspired terrorist" ran over two soldiers in a parking lot in Quebec, killing one and injuring the other before being shot to death by police.

Court records that appear to be Zehaf-Bibeau's show that he had a long rap sheet, with a string of convictions for assault, robbery, drug and weapons offenses, and other crimes.

Elizabeth May, the leader of the Green party, said in Parliament that the attacks were probably "the acts of isolated, disturbed and deeply troubled men who were drawn to something crazy."

"I do not believe that it was a vast network, or that the country is more at risk today than it was last week," May said.