Copies of the diaries reveal how Sivarasan planned to infiltrate a travel agency in the capital.
The agency is run by a distant relative of Rajiv Gandhi's close aide, Congress leader Mani Shankar Aiyar's wife Suneet.
An entry in Sivarasan's diary, which was seized by the CBI from a Tiger safehouse in July 1991, notes a 'V. Kalyasundaram, President Travel Service, 811 Arunachal Building, Barakhamba Road, Connaught Place, New Delhi-11'. Enquiries with the agency revealed that Kalyanasundaram worked there as assistant manager and moved out in 2004.