The Uttar Pradesh Police has formed a three-member Special Investigation Team (SIT) to probe the killing of gangster-turned-politician Atiq Ahmad and his brother Ashraf in Prayagraj, a senior official said on Monday.

Special Director General of Police (Law and Order) Prashant Kumar said the SIT was formed on the instructions of Prayagraj Commissioner of Police Ramit Sharma.

"In the investigation of the case pertaining to the murder of Atiq Ahmad and his brother Khalid Azim alias Ashraf on April 15 (Saturday) in police custody... Investigation is being carried out by the SHO of Shahganj police station," a statement issued by Sharma said.

"...In order to ensure (recording) statements/evidence of witnesses, compiling of records/electronic evidence, scientific/forensic evidence, examination carried out in the forensic science laboratory and to ensure impartial and qualitative investigation, this investigation will be carried out by a Special Investigation Team (SIT)," it added.

The statement added that Additional Deputy Commissioner of Police, Crime, Satish Chandra will be the SIT's chief investigator. Its other two members are Assistant Commissioner of Police (Kotwali police station) Satyendra Prasad Tiwari and Inspector, Investigation Cell of Crime Branch, Om Prakash.

In another statement, Uttar Pradesh Director General of Police R K Vishwakarma said a three-member team of supervisors has also been formed to ensure qualitative investigation and time-bound action.

This team is headed by the additional director general of police of Prayagraj. The other two members are the police commissioner of Prayagraj and the director of the Forensic Science Laboratory, Lucknow, the statement said.

Atiq and Ashraf were shot dead at point-blank range by three men posing as journalists in the middle of a media interaction on Saturday night while police personnel were escorting them to a medical college in Prayagraj for a check-up.

The brothers, both jailed in Prayagraj, were in handcuffs when they were killed in full view of camera crews around 10 pm. The last rites of Ahmad's son Asad, who was gunned down in a police encounter in Jhansi on April 13, were performed just hours before the shooting.

Police have registered a case under sections 302 (punishment for murder) and 307 (attempt to murder) of the IPC and provisions of the Arms Act and the Criminal Law Amendment Act against Lavlesh Tiwari, Mohit alias Sunny and Arun Maurya in connection with the killing of Atiq and his brother.

The Uttar Pradesh government on Sunday constituted a three-member judicial commission to probe the shooting.