"One person is being questioned in the case," City Police Commissioner M N Reddi told PTI here.
Bhavani, who hailed from Tamil Nadu and was on a visit to the city, succumbed to serious shrapnel injuries on her head in the blast on Church Street in the central business district of the city on December 28.
Four suspected Indian Mujahideen operatives were recently arrested here and at Bhatkal in Uttara Kannada district by Bengaluru police who claimed to have busted a terror module.