Pakistani national Abid Naseer was convicted of plotting attacks in several countries after being extradited to the US from the UK, where police believe they averted an "atrocity" by his detention.
As Abid Naseer started his cross-examination in a New York courtroom of the police officer who searched his Manchester bedroom in 2009, he commented it was nice to hear a Mancunian accent again.
Six years ago, the Pakistani national had been living in the north-west English city where he plotted to kill hundreds in a bombing attack at the city centre's Arndale shopping complex during Easter weekend.
Naseer, who was extradited from the UK to the United States in 2013, was convicted of providing and conspiring to provide material support to al-Qaeda and conspiring to use a destructive device.
Defending himself at his trial in New York, the 28-year-old was polite, calm and professional. He denied he was involved in any form of extremism.
But, according to the police officer who headed up the British investigation into his activities, his courtroom conduct was a performance designed to con the jury.
In a cafe overlooking the Brooklyn courthouse where the trial was held, Det Supt Mark Smith said Naseer was a good actor, an al-Qaeda trained terrorist and a man with a determination to kill hundreds of people.
He said: "He has had lots of time to develop his Westernised social skills, but I would say don't be fooled. Beneath that cool, relaxed exterior is a cold, calculated terrorist."