Najibullah Zazi testified against one of the co-conspirators in the New York plot

He was arrested in 2009 and is finally due to be sentenced in Brooklyn tomorrow

At the time the plot was discovered he was described as being the man behind ‘one of the most serious threats to our nation’ since the September 11 attacks

The ringleader of a plot to bomb New York City’s subway could get off with a lighter prison sentence tomorrow after he switched sides and offered valuable intelligence on al-Qaeda.

Najibullah Zazi – once described as the man behind ‘one of the most serious threats to our nation’ since 9/11 – has helped prosecutors to bring down other terrorists after pleading guilty to his role in the plot.

Seamus Hughes, deputy director of George Washington University’s Program on Extremism, predicted Zazi would also get ‘considerably less’ than a life sentence.

Prosecutors at the Brooklyn U.S. Attorney’s office ‘tend to look favorably on cooperation when it comes to terrorism cases,’ he said.

And the lengthy lag between Zazi’s guilty plea and sentencing, Hughes added, ‘speaks to the value that prosecutors saw in terms of Zazi testifying against others.’

Born in Afghanistan, Zazi moved to Pakistan as a child and then relocated to New York City as a teenager.

At age 14 he was living in Queens, where his father drove a cab. Friends said he initially seemed to like American life. He became a naturalized U.S. citizen and took a job operating a coffee cart on Wall Street.

Fellow food vendors said Zazi changed, though, after a series of trips back to Pakistan.

Seamus Hughes, deputy director of George Washington University’s Program on Extremism, predicted Zazi would also get ‘considerably less’ than a life sentence.

Prosecutors at the Brooklyn U.S. Attorney’s office ‘tend to look favorably on cooperation when it comes to terrorism cases,’ he said.

And the lengthy lag between Zazi’s guilty plea and sentencing, Hughes added, ‘speaks to the value that prosecutors saw in terms of Zazi testifying against others.’

Born in Afghanistan, Zazi moved to Pakistan as a child and then relocated to New York City as a teenager.

At age 14 he was living in Queens, where his father drove a cab. Friends said he initially seemed to like American life. He became a naturalized U.S. citizen and took a job operating a coffee cart on Wall Street.

Zazi (pictured after his arrest by the FBI in 2009) is due to be sentenced in federal court in Brooklyn on Thursday, and may escape without a life sentence

He grew a long beard, stopped wearing western clothes in favor of tunics and began playing holy music. He also ran into financial problems, declaring bankruptcy in 2008.

Not long after that, Zazi and two childhood friends from Queens- Ahmedzay and Adis Medunjanin – agreed to travel to Pakistan in 2008 to try to join the Taliban.

Instead, they were recruited by al-Qaida operatives for a ‘martyrdom operation’ on U.S. soil.

The plot called for the three men to conduct suicide bombings on subway lines during rush hour near the eighth anniversary of the Sept. 11 terror attacks.

Zazi, who had moved to a Denver suburb and briefly worked as an airport shuttle driver, later said he wanted to ‘bring attention to what the United States military was doing to civilians in Afghanistan by sacrificing my soul for the sake of saving other souls.’

He cooked up explosives in a Colorado hotel room, made from a recipe of beauty supplies.

Secretly, though, the FBI had gotten tipped off that Zazi was involved with militants.

He was placed under surveillance in Colorado and followed as he drove to New York, where police stopped his car as it entered the city. Officers let him go, but his rental car was later towed by the FBI.

Zazi was further spooked by a call from a Queens imam warning police were asking about him. He rushed back to Colorado.

FBI agents executed a series of raids. News outlets learned of the investigation and also began hounding Zazi, who told reporters he had no idea what was going on. He was soon arrested.

Obama-era Attorney General Eric Holder said Zazi was behind ‘one of the most serious terrorist threats to our nation’ since the September 11 attacks.

Other would-be terrorists have been able to gain their freedom by cooperating with prosecutors.