The RCMP tried to restrict the movements of Martin Couture-Rouleau weeks before he used a car to run down two Canadian soldiers in Quebec, but prosecutors said they didn't have enough evidence to obtain a peace bond, CBC News has learned.

His case is one of the reasons the federal government wants to make it easier for police to monitor and detain suspected extremists.

Couture-Rouleau's jihadist ambitions ended in St. Jean-sur-Richelieu, not far from where he ran down two soldiers, killing one of them, before being shot and killed by police following a high-speed pursuit.

Police knew the 25-year-old as a Muslim convert who made increasingly radical statements on social media and had arrested him in July before he could board a plane to Turkey, only to be told they had to let him go.

"We interviewed him and [with] the information we had and the statement he provided to us, we [did] not have enough evidence to charge him and to detain him," RCMP Supt. Martine Fontaine told CBC News.

Couture-Rouleau was released after RCMP seized his passport and added him to the 90 or so individuals on their watch list.

Now, CBC News has learned officers tried several weeks later to place Couture-Rouleau under a peace bond, which would have forced him to agree to meet certain conditions or go to jail.

Once again, prosecutors told police they didn't have enough evidence under the law, which says there must be evidence that a person will commit a terrorism offence.

RCMP, Harper say legal bar too high

The head of the RCMP told a Senate committee in the fall that police are being asked for too much evidence in their efforts to protect the public.

"Generally speaking, I'm of the view we need to be able to lower the threshold," RCMP Commissioner Bob Paulson told a meeting of the Senate's national security committee on Oct. 27.

He later told reporters, "I think it's a reasonable sort of area where we can examine on these peace bonds and other assistance orders."

Peace bonds have only been used eight times since 2001 for terrorism suspects — six of them related to members of the 2006 Toronto 18 plot, and two others.

Critics claim that's proof police aren't using the tools they already have. But government sources insist the current legal requirements put the tools too far out of reach.

"In recent weeks, I've been saying that our laws and police powers need to be strengthened in the area of surveillance, detention and arrest," Prime Minister Stephen Harper told the House of Commons on Oct. 23, the day after gunman Michael Zehaf-Bibeau killed Cpl. Nathan Cirillo at the National War Memorial and stormed his way into Centre Block on Parliament Hill.

The government's proposed changes will be unveiled when the Commons resumes later this month.

Among the targets of the legislation is the Passenger Protect Program, a Canadian version of the U.S. no-fly list that allows authorities to prevent anyone deemed to pose an immediate threat from boarding a plane.

Sources tell CBC News the government believes the program is another example of how police are handcuffed by excessive legal requirements in efforts to deal with potential threats before they happen.