The National Humans Resource Commission (NHRC) has issued a notice to the Uttar Pradesh police over killing of Atiq Ahmad and his brother.
Atiq Ahmad and his brother Ashraf Ahmad were shot dead by men posing as journalists on Saturday night, while they were being taken for a medical examination in Prayagraj.
Both the gangsters collapsed at the spot after being shot close to point-blank range.
Meanwhile, Union minister Giriraj Singh on Tuesday targeted Bihar Deputy Chief Minister Tejashwi Yadav for allegedly referring to slain gangster-politician Atiq Ahmad with an honorific, and said he should "hang photographs of the don in his office".
"I would suggest that the Bihar chief minister and deputy chief minister should hang photos of the PFI (Popular Front of India) and dons in their cabins," the Begusarai MP said.
"Earlier, Congress leader Digvijay Singh had referred to Osama Bin Laden as Osama ji. They can do anything for votes," he said.
"They have not uttered a word on the murder of Umesh Pal, why are they in pain now?" Singh added.
Tejashwi: It is not the death of Atiq ji, but the death of law
In controversial remarks, Yadav referred to the slain gangster as "Atiq ji" during a media interaction.
"It is not the death of Atiq ji, but the death of law that has taken place in Uttar Pradesh," Yadav had said.
Ahmad (60) and his brother Ashraf were shot dead at point-blank range by three men posing as journalists in the middle of a media interaction Saturday night while police personnel were escorting them to a medical college in Uttar Pradesh's Prayagraj for a checkup.
(with agency inputs)