Her most famous work was the book about a Seattle serial killer (Ted Bundy) who she was working alongside with, "A Stranger Beside Me".
http://www.cbc.ca/news/arts/ann-rule-true-crime-author-dies-at-age-83-1.3170564
http://www.cbc.ca/news/arts/ann-rule-true-crime-author-dies-at-age-83-1.3170564