WHO KILLED MARY ANN PLETT?

As reported by https://edmontonjournal.com/news/local-news/sept-15-1971-real-estate-agents-murder-remains-a-mystery, Mary Ann Plett was killed on September 15, 1971. The main suspect is James Cooper, a mysterious individual who was inspired by the writer James Fenimore Cooper. This correlation could be seen in some cases from the previous months and it is clear that the operation of the plane hijacking by