Maharashtra Anti-Terrorism Squad on Thursday filed a chargesheet alleging that Abhinav Bharat activist Praveen Mutalik was the key conspirator in the 2008 Malegaon blast that left six people dead.Mutalik was arrested by the ATS on January 31, this year from Gokak town in Belgaum district of Karnataka after evading police for over two years.Mutalik has been charged with various sections of IPC, Explosive Substances Act, Maharashtra Control of Organised Crime Act (MCOCA) and Unlawful Activities (Prevention) Act, 1967.The 305-page chargesheet claims that he had worked as a personal secretary to Lt. Colonel Shrikant Prasad Purohit, a key accused in the case, for three months before the blast. Purohit is in judicial custody now.Two other accused in the case – Ramji Kalangsara and Sandeep Dange – are still on the run. The ATS has so far managed to arrest 12 people in this case including Sadhvi Pragya, whose motorcycle was allegedly used to trigger the blast.