The Robison family were slaughtered in their Good Hart holiday home — To this day the case is unsolved — By the Summer of 1968, The Robison family was, financially, very successful. The household consisted of Richard and Shirley Robison, and their four children; Ritchie (19), Gary (17), Randy (12), and Susan (8). At the time of the crime, the Detroit-based family was staying in a summer house by Lake…