Supt. Martine Fontaine said authorities met with Martin Couture-Rouleau as recently as Oct. 9 and that there was nothing to suggest any such violent behaviour was in the offing. One of the soldiers struck by the car on Monday died.
"There was no indication then of his intentions," Fontaine told a news conference. "On the contrary, he seemed open to the idea of maybe taking measures to change his ways."
Mounties began investigating Couture-Rouleau, 25, last June when they saw on his Facebook account he was "radicalizing" himself.
"We couldn't arrest someone for having radical thoughts," Fontaine said. "It's not a crime in Canada."
Couture-Rouleau was eventually arrested and questioned in July as he was preparing to leave the country for Turkey.
"We weren't able to determine that he wanted to commit an act abroad," said the RCMP superintendent. "If we had had reasons to believe that Mr. Rouleau would commit a terrorist act or a criminal act, we wouldn't have let him go."
The investigation continued, with authorities meeting Couture-Rouleau on several occasions along with the imam at the mosque he went to.
Earlier, the RCMP commissioner said Couture-Rouleau had his passport seized because he was suspected of being an extremist with possible terrorist links.
Bob Paulson said the passport was confiscated and he confirmed he was one of 90 suspected extremists being investigated by the RCMP.
"That's what follows from the analysis; his passport was seized by us ...," Paulson told reporters after an appearance before the House of Commons house affairs committee.
"He was part of our investigative efforts to try and identify those people who might commit a criminal act travelling abroad for terrorist purposes. In that respect, we were working him and other suspects."
The government has raised its internal threat level due to an increase in "general chatter from radical Islamist organizations" such as the Islamic State of Iraq and the Levant, said Jason Tamming, a spokesman for Public Safety Minister Steven Blaney.
This level means that intelligence has indicated that an individual or group within Canada or abroad has the intent and capability to commit an act of terrorism, but it is not the result of a specific threat, he added.
Police said the car was driven deliberately into the two soldiers in what Blaney called an act of violence against Canada that was "clearly linked" to terrorist ideology.
Canada is taking terrorist threats seriously, Blaney said, adding he was "horrified and saddened" by Monday's incident in Saint-Jean-sur-Richelieu.
"What took place is clearly linked to terrorist ideology," he told a news conference in the town southeast of Montreal that is home to a military college and a garrison.
"It is an unacceptable act of violence against our country, our Quebec values, our Canadian values."
Police have said they shot the man following a car chase after he had struck the two soldiers with his vehicle in the parking lot of a shopping mall.
Provincial police identified the soldier who died as warrant officer Patrice Vincent, 53.
In the Commons, Prime Minister Stephen Harper praised him as a 28-year veteran who served with distinction across the country.
"This was a despicable act of violence that strikes against not just this soldier and his colleagues, but frankly against our very values as a civilized democracy," he said.
"We will continue to stand with the men and women of the Armed Forces who defend us against these threats."
Vincent served in Valcartier, Comox, Halifax, Trenton, Esquimalt, Edmonton, North Bay and Montreal.
Provincial police described the second soldier's injuries as less serious and said his life was not in danger.
Lt. Guy Lapointe told a separate news conference Tuesday that the act was deliberate and that one of the two soldiers was in uniform.
Blaney said that as far as he knows no order has been given to members of the Canadian Forces to not wear their fatigues in public.
Paulson said he does not believe the slain man had co-conspirators.
"We don't suspect that, but we're open to that and we're concerned about that, so we're going to be pursuing every investigative avenue to satisfy ourselves that we've eliminated that possibility," he noted.
On Monday, Lapointe said the shooting occurred after the man hit the two pedestrians in the parking lot of a shopping mall and took off.
That triggered a chase that ended with the man losing control and his car rolling over several times.
Lapointe said the man was brandishing a knife when he emerged from the vehicle.
Provincial police said Couture-Rouleau called 911 during the car chase to claim responsibility for hitting the soldiers.
— With files from Peter Rakobowchuk and Stephanie Marin in Saint-Jean-sur-Richelieu and Nelson Wyatt in Montreal
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