Where did Robert Arthur live?
This question is best answered by going to the Official Three Investigators web site. Elizabeth Arthur provides a complete biography of her father and describes how her father lived in various places over the years. However, he stayed with his aunt in his later years (when he was writing T3I stories) in Cape May, New Jersey. In fact, Elizabeth reveals that in "The Mystery of the Screaming Clock," Robert Arthur actually gave his street address, which was 309 Franklin Street.