A Canadian citizen with a history of mental health and addiction problems was sentenced Wednesday to 40 years in prison for plotting a Times Square subway attack that was thwarted by what a prosecutor said was the work of FBI agents working around-the-clock.

U.S. District Judge Richard M. Berman gave Abdulrahman El Bahnasawy, 20, of Mississauga, Canada, less than the life sentence requested by prosecutors but much more than what defense lawyers wanted.

“We can’t be sure the past is not a prologue to the future,” Berman said of El Bahnasawy’s 2015 and 2016 obsession with helping the Islamic State group. “We just don’t know in these matters. There is no room for error.”

The mother of the Kuwaiti-born defendant arrested in May 2016 interrupted the announcement of the sentence by walking from the courtroom shouting: “This is a sick boy! This is crazy! This is not justice!”

Earlier, her son had asked the judge for a “second chance,” saying he was “nowhere near the mentality” he was when he became radicalized online.

Two mental health experts told Berman during a four-hour sentencing hearing they believed El Bahnasawy no longer harbored an obsession with the terrorist group.

The judge noted El Bahnasawy’s six-year history of mental illness and addiction, which included treatment at facilities in Kuwait, Egypt, Canada and the United States for addictions and bipolar disorder. He’s also attempted suicide several times, the judge said.

Assistant U.S. Attorney George Turner had urged a life prison term, saying El Bahnasawy was not suffering from addictions when he pledged to strap an explosive to his body and kill as many people as possible.

“This was the real deal in the spring of 2016,” Turner said. “He chose Times Square and the subway system because they would be more crowded and more people would die.”

Turner said FBI agents in offices nationwide including in Washington, Los Angeles, Denver and Cleveland worked around-the-clock to infiltrate “a live terrorist attack.”

He said that through “skill and courageous undercover work, the FBI was able to win the trust of the defendant.”

Turner said El Bahnasawy did not deserve leniency, particularly after scrawling on a jailhouse wall images, threats and statements supporting the Islamic State group months after his capture.

During the investigation, an FBI undercover agent posing as an Islamic extremist communicated with El Bahnasawy by smartphone, according to criminal complaints. The papers say he at one point sent the undercover agent an image of Times Square with a smartphone message saying, “We seriously need to car bomb Times Square. Look at these crowds of people!”

The probe also resulted in the arrest of U.S. citizen Talha Haroon in Pakistan and a third co-defendant, Russell Salic, in the Philippines. Both men, who have denied being part of a terror plot, remain overseas pending extradition.

In October 2016, El Bahnasawy pleaded guilty to conspiracy to use a weapon of mass destruction and other charges.

Berman said he was not opposed to El Bahnasawy serving his sentence in Canada.

(AP)