Prabha Tyagi, mother of the deceased, lodged a complaint with the police against 10 people including Deputy Superintendent of Police (Special Task Force), Station House Officer, an advocate Ranjanvir Singh, and a juvenile who shot dead Tyagi in court yesterday, police said.
The complainant alleged that the accused had threatened Tyagi during police custody and the murder was a conspiracy in which police was also involved, they said.
An FIR has been registered in this connection, police said.
Tyagi was facing trial in the 2011 Barakali murder case in which 8 persons of a family were killed. Police had charge-sheeted 20 people in this case including him.
The victims, including former chairman of Cane Society Udayvir Singh, were killed after the jeep they were riding in was hit by a truck near Barkali village on July 11 that year.
Meanwhile, the juvenile, who was arrested on the spot, is being interrogated by the police. He would be produced in court today.