An official said the man had serious injuries on his body and was not taken to a hospital till late in the night.
A doctor at the district hospital, where he was eventually taken, told the media that he was brought with serious abdominal pain and vomiting.
Unnao Superintendent of Police Pushpanjali Devi said the four aides who took part in the beating have been arrested.
Inspector General of Police Praveen Kumar said a magisterial probe had been ordered.
An informed source said that District Magistrate Ravi Kumar N.G. went to the post-mortem centre to seek first hand information.
Sub-Divisional Magistrate Manish Bansal has been asked to submit a report to the government at the earliest.
Following the Chief Minister's orders, the Uttar Pradesh government suspended four police officers, including the Station House Officer of Makhi, Ashok Shukla, and three constables.
The probe has been assigned to Additional Director General, Rajeev Krishna.
Meanwhile Sengar told some reporters in Unnao that he was being framed by some people in a pre-planned manner to defame him.
Former Chief Minister and Samajwadi Party chief Akhilesh Yadav has meanwhile demanded the resignation of Adityanath over the incident. In a tweet soon after the incident came to light, he said it was shameful that such an incident had happened.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)