Police received reports that a man had been punched in the mouth after an argument with a group of men in the rear car park at Berkhamsted Sports Centre, off Douglas Gardens, just before 9pm on Saturday, April 2.
It has been said that the punch caused bleeding and gave the victim a dislodged tooth.
Detective Constable Karen Jordan, said: “The incident occurred following a boxing event at the location. Our enquiries are continuing at this time to identify the suspect and, as part of the investigation, we would like to speak to anyone who was present at the event so we can establish the circumstances around what happened.
She added: “If you were in the area at the time and saw the incident, or the events prior to it, please get in touch.”
Anyone with information is asked report information online.