Police are trying to track down the gunman who shot and killed a man in Morris Heights overnight.Investigators say 32-year-old Samuel Skerrett was found with a gunshot wound to the neck just a few yards from his University Avenue home. He was taken to Bronx Lebanon Hospital, where he was pronounced dead.Witnesses say Skerrett was ambushed by a man wearing a ski mask.Anyone with information is being urged to call Crime Stoppers at 1-800-577-TIPS.