A Waterville police sergeant has been disciplined by the department following a complaint from a homeless man who said the officer mistreated him. Brian Charette said in his complaint to police that Sgt. Brian Gardiner called him a “mental retard,” used profanity, threatened to use force against him, and sprayed saliva in his face during a confrontation in May. Following an internal investigation, police substantiated Charette’s complaint. In a letter to Charette, the department apologized for falling short “of the mark of professionalism that we all strive for.” Chief Joseph Massey tells the Morning Sentinel, that he cannot comment on the nature of Gardiner’s punishment. Charette, who has a criminal record, says he has had difficulty sleeping since the incident.