"A number of deaths have taken place. Santhosh was murdered. The Congress government is responsible for all these murders. I condemn this murder. Siddaramaiah is an irresponsible Chief Minister," Mr Yeddyurappa said.
28-year-old Santhosh was reportedly stabbed in the thigh and rushed to the hospital where he bled to death soon after. The police have arrested four men -- Wasim, Phillips, Umar and Irfan - in connection with his murder.
The police are citing personal enmity between Santhosh and Wasim as the reason behind the killing. "They had various issues, one of them was the sale of ganja (marijuana) by the accused," said Deputy Commissioner of Police C Rathore.
The BJP, however, has called it "political terrorism". "The same kind that we see in Pakistan," tweeted the BJP's Karnataka unit. The Rashtriya Swayamsevak Sangh (RSS), the BJP's ideological mentor, is also suspecting the killing to be politically-motivated.
"Santosh had organised a kabaddi match a fortnight ago and had put up a number of saffron flags around the ground, something that Wasim had objected to," said senior BJP leader and former deputy chief minister R Ashok.
The Congress attacked the BJP for "politicising Santhosh's death" at a time when the state prepares to vote for the new government.
Dinesh Gundu Rao, working president of the Congress in Karnataka, said, "It is unfortunate that Santhosh was killed. The police have made arrests. But the BJP is trying to politicise the incident. It is neither communal nor political. It shows how desperate the BJP is and what extent they can go to."
He added that the accused person is the son of a ward Congress president but it doesn't make any difference. "Action will be taken against the guilty," he said.
The RSS and BJP claim that 23 of their workers have been killed during the years of Congress rule. The state government denies this and says personal enmity or other reasons were behind at least some of those murders.