New Delhi: The CBI doubled the reward (raising it to Rs. 10 lakh) for providing clues to the mysterious murder of Shehla Masood who was shot dead on August 16 last year in Bhopal. Meanwhile the CBI has quizzed three persons after obtaining some clues. The identities of these persons have not been disclosed. The team has no intention of exhuming the body. More than 400 persons have been interrogated so far. In addition to investigation team, forensic experts from AIIMS are also camping at Bhopal.