John Oyimbo engaged in an exchange with the police over the allegation after murder suspect Henry Waswa was arrested following a hearing.
Oyimbo was accused of receiving a bribe after he defended Waswa, who allegedly shot and killed a Technical University of Mombasa student.
“What is your interest as the representative of the state when you want to fight others not to charge this criminal? We will expose you,” said one of the officers.
Oyimbo was further accused of stealing Waswa's file from the prosecution's office before he could be charged with defying an order to surrender his firearm license.
Waswa was not charged with the offense pending the recovery of the file.
Oyimbo had been dismissed from representing the DPP after the family of the slain student, Mitch Kibiti, accused him of aiding the suspect.
Police said Waswa and the armed youths intended to threaten witnesses.
They were arrested by Flying Squad officers who recovered two pistols, and are to be charged with the illegal possession of firearms.
Waswa had earlier requested the release of his passport for a trip to the United Kingdom for treatment.
Resident judge Abida Aroni who heard the case declined the application.
