The PCC chief described the recent custodial death in Jamui as a "criminal act".
Chaudhary said the suspension of two cops was not sufficient and they should be booked in a murder case.
Referring to police excesses in Jamui, Bagha and earlier in Forbesganj, the PCC chief said it appears that police in the state have gone "out of control". He urged Kumar to initiate steps in this regard because such approach of the police towards public would trigger anger among masses and situation could deteriorate.
"The government will be responsible for such bad condition," he said.
Congress general secretary and in-charge of Bihar affairs CP Joshi had said that voting in favour of Nitish Kumar was "tactical" and the party would not hesitate to agitate against his government on public issues.