The CBI on Saturday questioned BJP MLA Dhruv Narain Singh and his close aide Sanjay Gupta in connection with the murder of RTI activist Shehla Masood, in Bhopal.
Sources in the agency said though they had not found any conclusive links of the leader with the murder, he remains a suspect in the case.
The BJP leader is understood to have close relations with Masood as well as arrested alleged mastermind Zahida Parvez which resulted in the latter's resentment towards the activist, prompting her to order the killing.
The agency had recovered a personal diary of Parvez in which the investigators found several entries showing her obsession with the legislator.
The sources said Parvez who was an architect-cum-interior designer allegedly came in contact with the MLA in 2007 and developed an intimate relationship with him and the politician frequented her office.
CBI had found that Parvez and Masood knew each other and it was the former who had introduced the activist to the MLA.
Parvez kept a close eye on the friendship between Masood and the politician and allegedly went to the extent of trailing him along with her friend Farooqui. It was during one such surveillance that she found that he visited Masood's house and spent about half an hour there, they said.
During the questioning of accused - Farooqui, Saquib and Parvez - sleuths found that Parvez was so obsessed with the MLA that she had kept one office staff just for monitoring his movements and analysing call details through his bills, the sources said.
One entry in the diary on August 15 - a day before the RTI activist was killed - refers to the MLA saying, "Dhruv did not speak to me for two-three days but made a call to Shehla for half an hour," they said.