The Vigilance Investigation Bureau (VIB) on Tuesday arrested a sub-inspector of police while accepting a bribe in Bihar's Patna district, a press release said. The sub-inspector also attacked and injured a constable of the department, with a knife, while he was being arrested, the VIB release said. The sub-inspector, posted at Dhanarua police station in the district was accepting Rs 20,000 bribe for helping a complainant in a criminal case, the release said. One Ramesh Bhagat, a resident of Majhanpura village under the jurisdiction of Dhanarua police station of the district, had lodged a complaint with the vigilance bureau, it said. The man, in his complaint, said that sub-inspector Nathuni Ram was demanding a bribe of Rs 20,000 for helping him (Bhagat) in a case lodged with the Dhanarua police station, the VIB release added. The complaint was verified by the bureau and it found the allegation to be true, the release said. A vigilance team then raided and caught the sub-inspector red-handed, from the premises of Dhanarua police station, while he was accepting the bribe, the release said. The injured constable was administered first aid at a local hospital and then referred to Indira Gandhi Institute of Medical Sciences (IGIMS) in Patna, the VIB release added.