Authorities are investigating more suspects with connections to an alleged terrorist plot against a passenger train, sources with knowledge of the probe say.
With two men already in custody in Canada, a third man in the United States was questioned by FBI officials this week, a source said.
Raed Jaser, 35, and Chiheb Esseghaier, 30, are being charged with conspiracy to commit murder, participating in the activities of a terrorist group and conspiracy to interfere with transportation facilities.
On Tuesday, Mr. Jaser appeared in court in Toronto, Mr. Esseghaier in Montreal. Both remain in custody and say they will fight the charges.
The RCMP has offered few details of the alleged plot.
Sources who spoke to The Globe about the investigation, designated Project Smooth by the RCMP, were granted anonymity because they were not authorized to speak publicly on the matter.
They said the investigation evolved in three stages.
It began in the fall of 2011 when the RCMP and the Canadian Security Intelligence Service received tips suggesting that Mr. Jaser was spreading extremist propaganda to youth in Toronto.
Tight surveillance started the following year as the Mounties tracked one of his acquaintances, Mr. Esseghaier, during a trip to Mexico in May, when he was seen behaving erratically on his flight.
The RCMP went on to launch a formal investigation last August, leading to the arrests of Mr. Jaser and Mr. Esseghaier on Monday. According to the charge sheet tabled in court on Tuesday, the train plot was allegedly developed between April and September. The court document suggests that another individual interacted with Mr. Esseghaier as part of the alleged plot, although it contains no information on the person's involvement or identity.
In Toronto, Mr. Jaser's lawyer questioned the timing of the arrest given that police said there was no imminent danger to the population. John Norris noted his client was taken into custody in the wake of the Boston Marathon bombing and amid a parliamentary debate on a new federal anti-terrorism law.
"The timing of the arrest is a bit of a mystery and certainly I would like to hear the RCMP's explanation for that," Mr. Norris said. "I don't know what their purposes were, but their timing was notable to say the least."
However, the government said the RCMP maintained full control over the investigation and did not let political considerations influence its actions.
"Timelines for operational matters are dictated by our security and law-enforcement agencies only," said Julie Carmichael, a spokeswoman for Public Safety Minister Vic Toews.
Mr. Esseghaier was arrested while he lunched Monday at a McDonald's restaurant at the Via Rail Central Station in downtown Montreal.
He was quickly flown to a Toronto-area detention centre, but had to be ferried back to Montreal because the warrant for his removal to Ontario had not been authorized by a Quebec judge. Appearing handcuffed and wearing a black and blue parka, the former doctoral student made a point of protesting his innocence on Tuesday.
"These conclusions are being reached based on facts that are nothing but words and appearances," Mr. Esseghaier said before Judge Pierre E. Labelle cut him off.
"This is an initial appearance, not a time to consider the facts of your case," the judge said before Mr. Esseghaier was led away to be transferred to Toronto.
Mr. Jaser appeared before an Ontario Court justice of the peace at the Old City Hall courthouse in Toronto. "The accusations are very serious … my client is in a state of shock and disbelief that this is happening to him," Mr. Norris told reporters.
The court appearance lasted about five minutes and Mr. Jaser, bearded and wearing a tight-fitting head covering, told the justice of the peace that "it's quite clear" when he was asked whether he understood the proceedings.
Mr. Jaser's parents were in attendance during the court appearance. "I'm here to support my son … Let the police do their job," his father, Mohammed Jaser, told reporters.
Mr. Jaser's next court date was set for May 23.
Scores of police officers with rifles and search dogs surrounded a Toronto business called North York Moving and Storage on Monday, where Mr. Jaser is believed to have been employed, said Matt Sigman, a truck serviceman who works next door. Employees of the industrial strip mall said they were told to stay put for about two hours until police took a man with a beard into custody, said co-worker John Comes.
"He was inside the building. [Police] pulled him out and then they walked him to a black SUV."
Mr. Jaser was a director of Nexus Executive Limousine Services Inc., which was incorporated in 2008 and dissolved for non-compliance in 2011 after failing to file annual documents for three years, according to information from Industry Canada.
The business's registered office address was a house on Lehman Crescent in Markham, Ont. Property records show that Mohammed and Sabah Jaser bought the house in 2000. After mortgage payments were defaulted on, the lender sold it to another family in 2009.
Meanwhile, the Iranian government staunchly denied any involvement in the conspiracy, which RCMP said was guided by al-Qaeda operatives based in Iran. However, the RCMP did not characterize the alleged plot as a case of state-sponsored terrorism.
With reports from Paul Koring in Washington, Timothy Appleby and Renata D'Aliesio in Toronto and Ingrid Peritz in Montreal