"Russel was a young fellow in his 30s quite bright -- just about to get his Master's degree. ... And he really seemed like the last person to be murdered. And it became -- such a mystery," Rule said. " And in -- in the end they found, what I would think, were unlikely suspects."
Watch the video above to hear more from Rule, who wrote the book "Practice to Deceive" about the case.
"Practice to Deceive" is published by Simon and Schuster Inc., which is owned by CBS Corporation, the parent company of CBS News and CBSNews.com.