National Security Act (NSA) has been invoked against seven accused held in the December 3 Bulandshahr violence case, according to administration officials.
Police Inspector Subodh Kumar Singh, 44, and civilian Sumit Kumar, 20, were killed of bullet shots during the mob violence.
An FIR against 27 named people and 50 to 60 unidentified people was registered at the Siyana Police Station for the violence that was witnessed at Chingrawathi police post after cattle carcasses were found strewn outside nearby Mahaw village.
On January 3, the police had arrested local Bajrang Dal leader Yogesh Raj, also a key suspect in the case.
A separate FIR was lodged by the police for cow slaughter on a complaint by Yogesh Raj.
So far, over 35 people have been arrested in connection with the violence, including Army jawan Jeetender Malik, Prashant Nat who allegedly shot the inspector dead and Kalua who had attacked him with an axe, the police said.