New Delhi, July 14 -- Evidence collected by the Federal Bureau of Investigation (FBI), including intercepted conversations and emails between Tahawwur Rana, David Coleman Headley and Lashkar-e-Taiba (LeT) planners in Pakistan, forms the key basis of conspiracy charges filed earlier this week by the National Investigation Agency (NIA) in the 26/11 Mumbai attacks, according to officials familiar with the development. The federal agency on Wednesday filed a supplementary charge sheet calling the Pakistani-born Canadian citizen a "key conspirator" based on his interrogation and evidence collected, both by it and the FBI, which was also part of extradition documents. For instance, the FBI recorded a conversation between Headley and Rana when they took a long car ride on September 7, 2009, in which they discussed the Mumbai attacks, Rana's appreciation for LeT, his meeting with Abdur Rehman Hashim Syed alias Pasha (a former major in Pakistan army and 26/11 handler) in Dubai, giving Nishaan-e-Haider (Pakistan's highest military honour to nine attackers) and the future plan to attack the National Defence College (NDC) in India. Subsequently, in email conversations on August 11 and 17, 2009 between Headley and Sajid Mir (a top LeT operative), retrieved by the FBI, discussions took place with regard to Rana praising Mir for planning the attacks in Mumbai. The FBI had also recovered travel details of Rana to Dubai, where he met Pasha just before the 26/11 attacks. "All these conversations form the evidence of conspiracy, in which Rana had actively taken part and base the charges in the court," said an officer, who asked not to be named. This officer explained that the Indian Evidence Act has the provision to allow evidence submitted elsewhere to be used in trial in India. The FBI had also recovered the memory cards containing videos and photographs of various locations in India provided to the co-conspirators in Pakistan for the purpose of planning attacks, maps and books of targets, false immigration documents prepared by Rana for Headley for obtaining a five-year business visa for India, financial documents establishing Rana wiring money to Headley on four occasions during latter's trips to India, and details of payment of expenses associated with the Immigrant Law Centre office of Rana in Mumbai (which acted as a cover for the surveillance activities of Headley), according to a second officer. Importantly, the Indian investigators have also used the testimony of Headley - an NIA team questioned him in the US in June 2010 - to build a case against Rana and to establish that they were close friends who attended a military boarding high school together in Pakistan, and discussed all aspects of 26/11 conspiracy on a regular basis. The NIA also gathered substantial evidence against Rana and Headley during its probe, which was also shared with the US during extradition proceedings, and has been included in the latest charge sheet as well....