The police said they were yet to confirm the political affiliations of the man, or the motive behind the gruesome murder.
The 28-year-old, was on a motorcycle when four men in a car forced him to stop at Katipalla, a town in Dakshina Kannada district about 12 km from Mangalore. Deepak Rao, also known as Deepy, was attacked with sharp weapons and died on the spot, the police said.
Rajesh Padamar, Karnataka Media Coordinator of the Rashtriya Swayamsewak Sangh, later tweeted that Rao was "an active volunteer" in various activities of Bajrang Dal and BJP locally.
The Bajrang Dal state coordinator Suraynarayan also said Deepak Rao used to participate in the activities of the outfit.
This is the second instance where either the BJP or its ideological mentor Rashtriya Swayamsevak Sangh (RSS) have made a similar claim.
The mysterious death of a 21-year-old, Paresh Mesta, had escalated the political row between the Congress and the BJP last month. The BJP had demanded a probe into Paresh Mesta's killing by the National Investigation Agency, claiming that he was linked to Hindu right-wing groups.
His father, however, had denied that his son was associated with any organisation.