By Isabel Cassidy HOMICIDE detectives who investigated the murder of 14-year-old Shirley May Collins (pictured), whose battered body was found in September 1953 at Mt Martha, described the murder as “one of the most vicious and sadistic in the history of Victoria”. The investigation was said to be one of the biggest and most intensive manhunts in the history of Australian crime. Shirley Collins was described as a young, shy, smiling and innocent girl. Her father had died and her mother remarried and moved to Queensland. She was one of four foster children living with her foster parents, Mr and…