The DCI is investigating Mumias East MP Benjamin Washiali on allegations that he assaulted a man accused of siphoning fuel from a tractor in 2015.
A video clip that surfaced on social media in January shows the MP kicking and slapping the unidentified man after accusing him of siphoning fuel from a tractor that was transporting cane to Mumias Sugar Company.
Mr Washiali explained his actions but said those who circulated the clip were out to undermine him politically.
"I was angered that while we strive to have the factory stable, some people are determined to bring it down and undermining our efforts," he said.
"I had only two options, to take him to the police so that he is arrested and ruin the rest of his life, or give him a few slaps and make him understand that what he was doing was wrong."
The MP said, however, that he regretted his actions.
"Time is a healer and I must apologise to the public because, even though the beating was not fatal, as a leader, I shouldn't have taken that route," he said.
The video resulted in calls for the MP to be arrested and prosecuted as his supporters claimed it was being used to tarnish his name.
Shem Nyamboki, Western Region Criminal Investigation Officer, said the matter was reported at a police station in Mumias but that action was never taken.
Mr Nyamboki said on Thursday that police had recorded a statement from the man and were expecting Mr Washiali to give his.
"We have made good progress with a view to questioning the MP and taking appropriate action," he said.
Police have obtained medical records indicating the man was treated after he was assaulted near a sugarcane farm.