"Rana's only crime was to be friends with David Headley and to be in business with David Headley. David Headley betrayed that," Charlie Swift, who is also an attorney in the US military was quoted as saying by the Chicago Tribune.
Rana did nothing more than open his business to a friend, he said.
The arguments in the trial of 50-year-old Rana, co-accused with Pakistani-American Headley, will be heard by a 12-member jury later on Monday.
Headley, 50, Rana's old friend from military school in Pakistan, claims that two years before terrorists struck Mumbai, he began laying the groundwork for the attack, financed by USD 25,000 from an officer in Pakistan's powerful intelligence service.
Rana, who was indicted by a federal grand jury under 12 counts on February 15 last year for planning the attacks, providing material support to the Lashkar-e-Tayiba to carry out the attacks and guiding Headley in scouting targets in Mumbai in the process.
Arrested in Chicago over the Mumbai attacks, Rana had claimed that he provided "material support" to 26/11 terrorists at the behest of Pakistani government and the Inter-Services Intelligence. If convicted, Rana faces a possible life sentence. While Headley has pleaded guilty, Rana has not pleaded guilty.
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