As can be seen, Z340 associates with the fake ciphers. Interestingly, the other true ciphers form their own cluster, away from Z408, implying that the encryption mechanism used for them is a lot stronger than the encryption mechanism of Z408.
A fake or not a fake?
Other tests Juzek describes in his paper strengthen the nonsense hypothesis, too. Nevertheless, Juzek’s work is not a proof that Z340 is a fake cryptogram (and Juzek doesn’t claim that it is). However, Juzek has delivered some interesting evidence that supports the hoax hypothesis.
Generally speaking, the nonsense hypothesis appears to make sense. I can well imagine that the Zodiac Killer wanted to create an unsolvable crypto mystery, after his first encryption had proven weaker than he had expected. Perhaps, to be on the safe side, he decided to create an encrypted message that is unsolvable because there is no solution.
If you follow Juzek’s arguments or if you have a different opinion about Z340, please let me know.
Further reading: The Zodiac Killer code is solved – at least in this new movie