CHICAGO (CBS) — Closing arguments are expected later Tuesday in the trial of a Chicago businessman accused of helping plan the Mumbai terror attacks.

On Monday, jurors got a glimpse of how the defendant, Tahawwur Rana, responded under questioning by federal investigators.

“I am not guilty. I maintain that,” Rana says under questioning during the six-hour interview.

Rana is charged with covering up for David Coleman Headley, who has pleaded guilty to his role in the Mumbai attacks which killed more than 160 people including several Americans.

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Also on Monday, Rana’s defense team rested its case after calling only two witnesses — a computer expert and immigration attorney.

Earlier, Headley was the prosecution’s star witness in the trial, on the stand for nearly a week telling jurors how he worked with Pakistani intelligence and a militant group ahead of the bombing.

Headley has pleaded guilty to laying the groundwork in the three-day massacre that left more than 160 dead in India’s largest city.

So far, he has told jurors that in August 2009, he used one of Rana’s work computers in Chicago to begin researching details about Lockheed Martin and its CEO for Ilyas Kashmiri, a Pakistani terrorist leader who has ties to al-Qaida.

Kashmiri, one of six others charged in the Mumbai case in absentia, was reportedly killed Friday in a U.S. missile strike. Rana is the only one on trial.

Headley said Kashmiri was angry over the U.S. drone attacks inside Pakistan and wanted to target the defense contractor.

Kashmiri led the militant group Harakat-ul-Jihad al-Islami, which has launched attacks in India and Pakistan, including a 2006 suicide bombing against the U.S. consulate in Karachi that killed four people, according to the State Department.

Headley also has pleaded guilty to plotting an attack against a Danish newspaper that in 2005 printed cartoons of the Prophet Muhammad, which angered many Muslims. Rana is also charged in that plot, which was never carried out.

Rana and Headley were high school chums, and defense attorneys have described Headley as liar who cut a deal with the government to avoid the death penalty.

Rana, a Canadian national who has lived in Chicago for years and owns an immigration services business on Devon Avenue, has pleaded not guilty.

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