The Delhi Anti-Corruption Bureau arrested a Delhi Police head constable on Friday for accepting a bribe of Rs 20,000. A source in the ACB said they had received a complaint wherein the victim alleged that the cop, posted in the Sonia Vihar police station, threatened to implicate him in a police case. CM Kejriwal has vowed to fight corruption in the national capital and vowed to make it graft-free in the next five years.