Prasad Avatka had shared a controversial tweet by Bajrang Dal activist Bhuvit Shetty, posted after Dr Kalburgi's murder. Shetty had deleted the tweet, but he was arrested on Monday and later released on bail.

Avatka was a member of Bajranj Dal for 8 years, after which he joined Sri Ram Sene. But he quit the group, which is notorious for moral policing.

Avatka had been in jail in 2010 in connection to another case, was booked this time for promoting enmity between different groups and criminal intimidation.

The Bajrang Dal, affiliated to a group of organisations led by the BJP's ideological mentor Rashtriya Swayamsevak Sangh, held several protests against Professor Kalburgi last year.

Dr Kalburgi, 77, the former vice chancellor of Hampi University, had provoked the groups by speaking in support of noted author UR Ananthamurthy when he shared that as a child, he had urinated on stone figurines.

The professor had received many threats to his life, say family and friends. Last year, he was given police protection, which was removed after three months on his request.

He was shot dead on Sunday at his home in Karnataka's Dharwad by gunmen who came on a bike, rang his doorbell and asked to meet him.

The police have released the sketches of the two men, but no arrest has been made in the case yet.

The state government has said the case will be handed over to the Central Bureau of Investigation.