Just don't go in expecting your typical crime film ending.
Other investigators have raised questions about some of Graysmith's methods and documentation. But Arthur Leigh Allen is still a top candidate.
Here is the most well-known site on the subject: http://www.zodiackiller.com/
The thing about ALA is that so much circumstance stuff pointed towards him, but, if I understand correctly, hard evidence couldn't prove he was the Z.
That was a few years ago, and some used it to dispute Graysmith, but - as it says on that site - the DNA later came into question because it turned out it came from the outside of the stamp rather than the inside. As I remember, the guy who runs the site was one of those who disparaged Graysmith, but looking at his site again he has re-elevated ALA. I believe his choice is Gaikowski.
BTW, you came up with a cool handle.