Munna was allegedly beaten to death on Sunday in a land dispute.
The committee comprises ASP Kheri, Circle Officer Sidhauli and inspector crime branch.
The committee will probe the role of Circle Officer Kuldeep Kukreti and other policemen and will submit its report within three days.
Kukreti has been attached to the police headquarters while a chowki in charge and two beat constables have been suspended.
The action was taken late Sunday night after the opposition mounted a blistering attack on the state government over the incident.
Earlier, dismissing the deceased legislator’s family’s allegations, Lakhimpur Kheri SSP Satendar Kumar had said that the former MLA “accidentally fell on the ground during the argument with the other party”.
The post-mortem report states cardiac arrest as the cause of death and has no mention of injuries.
The three-term MLA was taken to the hospital but succumbed to injuries on the way.
Mishra and his son, Sanjeev, were earlier charged under sections 107/116 of CrPC in the same case for “disruption of peace'”.
Addressing the media, Sanjeev said: “A case is pending over our ancestral land and the members of other party came along with a group of 50-60 people despite lockdown and police presence. They were ploughing the land and when we stopped them, they started thrashing me.
“When my father tried to intervene, they also thrashed him. He had died on the spot. We took him to a hospital in Palia with the support of locals. Few members of the opposite party were caught by the villagers but later Circle Officer Kuldeep Kukreti arrived in the village with police force and he thrashed my wife and mother and rescued all of them.”
The incident soon took a political turn with Samajwadi Party president Akhilesh Yadav tweeting that “under BJP’s rule, the public is not just tense about law and order, but scared too”.
The state’s Congress unit tweeted: “Another Brahmin killed. The jungle raj in UP is getting frightening.”