This was because Bhatt had handed over, about 600 pages of documents to the Central Bureau of Investigation which could incriminate several politicians, police officers and bureaucrats for their active connivance in engineering the riots of 2002, whose countless victims are still struggling for justice.
http://ummid.com/news/2011/October/07.10.2011/sanjive_bhatts_arrest.htm
http://ummid.com/news/2011/October/07.10.2011/sanjive_bhatts_arrest.htm