Keep in mind that many of the letters this site will visit are in fact manipulated handwriting. Zodiac Killer thrived on anonymity, and indicated that he was capable of fooling everyone. Claims are from leaving no fingerprints or evidence to the Scorpion Letters where he indicates that he knows how to write so that he cannot be identified and he can beat Police, FBI, and finally CIA code breakers.
The only problem with this is that the body can only achieve what the mind can conceive, so I will show you what individual letters he disguised, and how they are consistent with all the serial killing letters in this research. Even better yet, I will show you how the authors used the same allographs in their attempt to disguise.