The CBI on Tuesday, grilled former UP Minister Babu Singh Kushwaha, once a close aide of UP Chief Minister Mayawati, for nearly eight hours in connection with National Rural Health Mission scam and murders of two Chief Medical Officers who were killed during his tenure in Lucknow.AIR correspondent reports that former Family Welfare Minister Kushwaha arrived at CBI Headquarters Tuesday morning where he was questioned about alleged swindling in 10,000 crore rupees central funds allocated for the scheme.