Surely the worst candidate ever?
At least Lewis Carroll, Walter Sickert and James Maybrick were in England at the time of the murders. Van Gogh was in Arles!
Although I'm not pro any suspect I recall the words 'amateurish fake,' being used with regard to the diary as soon as it appeared (a bit too quickly actually). So you'd think that after 26 years or so someone would have come up with that absolute, inarguable, killer fact to disprove it. Surely just unanswered doubts don't constitute a definite forgery. Of course it might be a forgery but I seem to recall the Hitler Diary being exposed conclusively in less than a year.