The politician will be investigated for criminal conspiracy. He was forced to resign from office on Tuesday after he was accused in a police case of criminal conspiracy.
Parveen Azad, the widow of the police officer, says her husband was killed on the orders of Raja Bhaiya, whose real name is Raghuraj Pratap Singh. She says he could influence the investigation and has demanded that he be arrested immediately.
Chief Minister Akhilesh Yadav told NDTV on Wednesday night that "whichever minister has been involved in wrongdoing, we will definitely order an enquiry." (Watch)
The assurance lacks credibility. Despite the enormity of the charges against him, the police has yet to question or arrest Raja Bhaiya.
Deputy Superintendent of Police Zia-ul-Haq was killed when he arrived in Pratapgarh to investigate the shooting of the village headman and his brother. An angry mob confronted the police man. (Read: How Zia-ul-Haq was killed)
A post-mortem report shared yesterday by the Uttar Pradesh police shared explicit details of how he was attacked - there serious injuries on his head, several ribs were fractured, injuries prove he was dragged for several metres on the ground and he was shot in the chest.
His revolver and the bullet that killed him are missing.