A Pakistan-born Chicago businessman was part of the “inner circle” of terrorists who plotted the 2008 Mumbai attacks, US prosecutors said in closing arguments on Tuesday.

Tahawwur Rana’s trial was closely watched as it touched on Pakistani military intelligence collusion with terrorism — a hugely sensitive subject since the killing of Osama bin Laden last month sparked similar US allegations.

Rana, a 50-year-old Canadian citizen, is charged with providing material support to terrorists by acting as a messenger and providing a cover for a key figure in the bloody 60-hour siege of India’s largest city in which 166 people died.

“When it’s all said and done, this is a simple case about awful things — two terror plots,” prosecutor Victoria Peters told jurors. “One that was carried out and one that was, mercifully, stopped.”

Peters cited coded emails and a lengthy conversation, taped by the FBI, between Rana and confessed conspirator David Headley as evidence of his involvement and support for the Mumbai attacks and a second plot on a Danish newspaper.

Headley, Rana’s old friend from military school in Pakistan, has been cooperating with prosecutors since his 2009 arrest at a Chicago airport and was the star witness during the trial.

When it emerged last month that Bin Laden had hidden for years in a Pakistani garrison town before being shot May 2 by US Navy SEALs, serious questions were raised about the possible collusion of Pakistan's military.

Pakistan’s powerful Inter-Services Intelligence (ISI) agency has long been suspected of involvement in the Mumbai attacks and three ISI agents were named as co-conspirators by US prosecutors.

Rana insisted after his 2009 arrest that he was a pacifist who was “duped” into letting his old friend use his immigration services company as a cover for his scouting missions to India and Denmark.

Defence attorney Patrick Blegen told jurors Rana had no knowledge of Headley’s terror plots and was instead “used” by his friend as he urged jurors to render a verdict of not guilty.

“Nothing is simple when it comes to David Headley, he is a lifelong manipulator,” Blegen told jurors. “David Headley thinks he can fool everybody. Don’t let him fool you.”

Headley testified that he believed the ISI’s involvement in the Mumbai plot was limited to a handful of rogue agents but that he believed the ISI worked closely with the banned militant group Lashkar-e-Tayyaba (LeT).

But, in summing up, Peters returned repeatedly to a transcript of a secretly taped conversation that showed Rana laughing about the Mumbai attacks and saying that the men who carried out the siege should be given “the highest honors.”

“The Tahawwur Rana you hear chatting freely about terrorism in this car ride with his childhood friend David Headley is no dupe,” Peters said.

“These two old friends didn’t just talk about past accomplishments, they talk about future targets.”

She pointed to a Dubai meeting Rana described having had with Abdur Rehman Hashim Syed, a retired major from the Pakistani Army who connected Headley with Al Qaeda military commander Ilyas Kashmiri and was known as “Pasha.”

“Rana says in this conversation that Pasha had given him the warning in Dubai that the (Mumbai) attack was imminent,” Peters said.

“What does it tell you about Rana that Pasha gave him this warning? Pasha knows that Rana is part of the inner circle. Pasha knows he can trust Rana.”

Peters told jurors that she believed the government had proved beyond a reasonable doubt that Rana knowingly provided material support to terrorism in both plots and asked them to find him guilty on all three counts.

Headley formally admitted to 12 terrorism charges in March 2010 after prosecutors agreed not to seek the death penalty or to allow him to be extradited to either India, Pakistan or Denmark to face related charges.

A date has not yet been set for his sentencing.

In a plot that reads like a movie thriller, Headley spent two years casing Mumbai, even taking boat tours around the city’s harbor to identify landing sites for the attackers and befriending Bollywood stars as part of his cover.

India and Washington blamed the Mumbai rampage on Pakistan’s banned militant group LeT. The attacks stalled a fragile four-year peace process between the two South Asian neighbors and nuclear-armed rivals, which was only resumed in February.