The American agent, who testified under the fake name Tamer El-Noury to protect his real identity, spent two and a half weeks on the stand in a Toronto courtroom.
It was the same name the agent used when he befriended Raed Jaser and Chiheb Esseghaier while working undercover on the RCMP investigation— called "Project Smooth" — from June 2012 until the pair's arrest in April 2013.
While much of his time was spent with Esseghaier, the FBI officer, who pretended to be a wealthy businessman with radical views, also spent considerable time with Jaser in September 2012.
Those interactions — many hours of conversations secretly recorded by the agent — formed the bulk of evidence in the case.
While his identity is protected by a court-ordered publication ban — a directive taken so seriously that the public and media were not allowed to be in the courtroom during his testimony, the agent did give the jury an idea of his background:
— He was born overseas.
— Arabic is his first language, although his English is flawless.
— He is a practising Muslim.
— He previously worked as a police officer, first in general crimes and then in narcotics, where he became an undercover officer who worked in the field for 12 years.
— He joined the FBI's counter-terrorism division in 2008 and has been working as an undercover agent ever since.
It also became apparent during trial that although the agent posed as a radicalized individual, the hateful tirades of the accused in the case did grate on him at times.
"The religious views that are presented are a complete desecration of my religion," the agent said at one point during his testimony, reflecting on Esseghaier's justification for the killing of innocent women and children.
The character the agent took on in his undercover role in this case was that of a "foreign-born Muslim American" who was a wealthy real estate developer with a "radical mindset," he told the jury.
Before first coming into contact with Esseghaier on a flight where they sat together in June 2012, the agent developed a "legend" or cover story, to flesh out the person he was pretending to be.
In this case, the agent pretended to be someone who had drifted away from his religion after being Americanized, but through "tragic personal events," including the death of his mother, returned to Islam and was radicalized by an uncle.
"It's sort of a dance when you do undercover work," the agent told the court during his first day on the stand. "You don't want to put out your entire legend or cover story when you meet someone....it's a natural human nature relationship...the only difference is obviously your background is made up."
The trial has heard that Jaser and Esseghaier allegedly plotted to derail a Via Rail passenger train travelling from New York to Toronto. They allegedly planned to carry out the plot with financial backing from the character played by the undercover agent.
Jaser and Esseghaier were arrested in April 2013.
Jaser pleaded not-guilty and Esseghaier, who did not want to participate in his trial, had a not-guilty plea entered for him by the judge presiding over the case.