A former Chelsea cop admitted to punching a person in custody and lying about the circumstances of his arrest, Suffolk County District Attorney Dan Conley said. 

Felix Rivera of Lynn pleaded guilty to assault and battery and filing a false report on Tuesday.

Suffolk Superior Court Judge Peter Krupp continued that charge without a finding over prosecutors’ objections. If Rivera stays away from the victim, takes part in an anger management program, and undergoes a mental health evaluation and any treatment deemed necessary, the court will dismiss that charge in two years.

Chelsea cops responded to 155 Chestnut St. that night for a report of a man with a gun on September 26, 2014. The victim was at the scene, and appeared drunk, according to police, and was arrested for allegedly interfering with the investigation, Conley said. 

But as the handcuffed man was being escorted away, Rivera punched him four times in the face, knocking him to the ground. Another officer reached out to stop him, Conley said. That officer, who prosecutors did not name, denied the allegation in Rivera’s report that the victim had put up a fight while being led from the scene. 

“We maintain that a felony conviction was appropriate to these facts,” Conley said in a statement. “This wasn’t police work. It was criminal conduct.”