The CBI has registered four cases in connection with the killings of a DSP and two others in Uttar Pradesh and related violence.

The agency also named former Uttar Pradesh minister Raghuraj Pratap Singh, alias Raja Bhaiya, in one of its four FIRs. Earlier, the central government handed over the murder case to CBI for probe.

AIR correspondent reports, Slain DSP Zia-ul-Haq, posted as Circle Officer in Kunda town, was allegedly killed by a mob in Pratapgarh when he had rushed there after village head and his brother were shot dead over a land dispute.