It's a homicide case that has stumped police for more than 20 years.

On July 10, 1988, members of a recreational dive club found a dismembered human head at the bottom of a river in Peterborough, Ont.

Despite conducting an extensive air and underwater search, police were unable to find the remainder of the victim's body. Investigators were also unable to identify the man. But 26 years later, police are hoping that newly released two-dimensional renderings of what they believe the victim may have looked like at the time of his death may help them solve the case.

Police say the victim's head was located approximately 39 metres from the Otonabee River's shore, near Lock and McKellar Streets. Investigators believe the victim was between 40 and 74 years of age. Some lower molars were missing from the man's jaw prior to his death, and staining on his remaining teeth indicated that he was a smoker.

Police also believe the victim was bald or partially bald. He had a small amount of facial hair, which investigators believe may have been a dark colour.

At the time the dismembered head was found, police say there were no outstanding missing male persons reports in Peterborough. Investigators say this suggests that the head may have been brought to the area from elsewhere.

"It is not known how long the head was in the river, or when this man was killed," police said in a statement on Thursday.

Anyone with information is asked to contact Peterborough Lakefield Community Police at 705-876-1122, ext. 555 or Crime Stoppers at 1-800-222-Tips.