Yes, Stephen Knight's book came out in the early 70s with his theory that Dr. Gull was Jack the Ripper and suggested involvement of the Freemasons in a cover-up. It inspired Bob Clark's excellent Sherlock Holmes movie "Murder By Decree" which dealt with the same subject.

There is also a school of thought that says Jack the Ripper was the insane misogynist Prince Albert Victor, the Duke of Clarence (son of future king Edward VII and nephew of Old Queen Vicki).