The crime thriller film Zodiac left too many unanswered questions for us. One of them is the similarity between the handwriting of Bob Vaughn (who used to work with Rick Marshall, one of the Zodiac suspects) and the handwriting in the Zodiac letters. Since Arthur Lieh was considered to be the real Zodiac killer, this handwriting mystery remained unsolved as Bob Vaughn had nothing to do with Arthur Lieh (apparently). Does there exist an explanation? I will be delighted to have one.