A man arrested in a U.S. terror plot in New York April 22 was a graduate student studying chemical engineering at Laval University in Quebec City, CBC News has learned.

Ahmed Abassi's major is "particularly chilling" in conjunction with other evidence presented against him by the FBI, said CBC's Greg Weston.

The FBI alleges Abassi was plotting to kill upwards of 100,000 people by contaminating the air or water supply in a major U.S. city. However, the plan did not materialize any further than discussions.

Abassi is also being  linked to Chiheb Esseghaier, one of two Canadian residents recently arrested in Canada in connection with an alleged plot to derail a Via passenger train.

The RCMP said it worked closely with the FBI during the RCMP's investigation into Esseghaier and his co-accused, Raed Jaser. The FBI's parallel investigation led to the charges against Abassi.

"Through our efforts, we assured that at no time did this individual pose an imminent threat to public safety in Canada," said Sgt. Greg Cox.

Unclear how Abassi entered U.S.

American investigators have accused Abassi, 26, of fraudulently applying for a visa to stay in the United States to "facilitate an act of international terrorism."

"Abassi had an evil purpose for seeking to remain in the United States — to commit acts of terror and develop a network of terrorists here, and to use this country as a base to support the efforts of terrorists internationally," U.S. Attorney Preet Bharara said in a statement.

Abassi travelled to the U.S. in March, said Weston. However, he did not enter the country directly from Canada.

CBC News has learned Abassi left Canada for Tunisia before Dec. 25, 2012. Abassi never returned to Canada, Weston reported.

Abassi had trouble obtaining a visa to return to Canada, Immigration Minister Jason Kenney said when answering a question at a news conference.

Kenney said immigration officials became aware of security concerns while he was in Tunisia and he believes officials did not renew Abassi's study permit.

Canadian law enforcement sources say Abassi had been under surveillance by RCMP and CSIS agents for months before he left for Tunisia and subsequently resurfaced in New York.

But a senior government official told CBC News that Abbasi's student visa did not allow him to leave the country during his studies without re-applying for an entry permit to Canada.

The official said it was Abassi's subsequent application for a re-entry permit to Canada that raised red flags on his file with visa officers at the Canadian consulate in Tunisia, and the permit was denied.

It's unclear how he entered the U.S.

Weston said Abassi's route is important, because of an American perception that Canada is a breeding ground for alleged terrorists.

May have radicalized 2 Canadians

Abassi allegedly played a key role in radicalizing at least one of the two Canadian residents arrested last month in an alleged plot to derail a Via rail train.

U.S. investigators say that while they were monitoring Abassi, he met with Esseghaier, 30, in New York City.

Officials noted in the statement that Esseghaier was "previously radicalized by Abassi."

In New York City, Abassi, Esseghaier and an undercover agent discussed their plans. The statement says Abassi "discussed his desire to engage in terrorist acts against targets in the United States and other countries, and his intention to provide support and funding to organizations engaged in terrorist activity."

In an interview with law enforcement officers, Abassi acknowledged that he "may have radicalized" Esseghaier, and said the two "discussed plots to poison a water system and to derail a passenger train," U.S. prosecutors said in a letter filed by U.S. prosecutors with a New York court.

The indictment charges Abassi with two counts of knowingly making false statements to immigration authorities to facilitate an act of international terrorism. Abassi may face further undisclosed charges at a later date, according to the letter.

Canadian authorities arrested Esseghaier, 30, and Toronto-area resident Jaser, 35, last month for allegedly planning to carry out an attack against a passenger train travelling between the U.S. and Canada.

Authorities arrested the trio on the same day, but the FBI kept Abassi's detainment quiet until Thursday.

Corrections

  • An earlier version of this story said incorrectly that Ahmed Abassi studied at a Montreal university and that he studied chemistry. In fact, he studied chemical engineering at Laval University in Quebec City.
    May 10, 2013 5:06 PM ET
With files from CBC's Greg Weston