The biggest names in it were two Trinamool Congress MPs - journalist Kunal Ghosh and Srinjoy Bose, owner of the Bengali daily Pratidin.
The letter described how they fleeced him of crores, with the Pratidin owner even guaranteeing him 'state protection' as he and Ghosh had "a very close connection" with chief minister Mamata Banerjee.
Threatening suicide, Sen wrote he had been deceived by people with top police, bureaucratic and political connections and the letter could be treated as his "last wish" and "an FIR".
He also described how the money could be recovered by selling the assets of his company. Giving the whereabouts of the deeds of the properties, he asked the CBI to take possession of them.