In addition to the evidence cited in other replies, this solution has now been verified by the FBI, who has in the past dismissed other supposed "solutions" as

In addition to the evidence cited in other replies, this solution has now been verified by the FBI, who has in the past dismissed other supposed "solutions" as the kind of thing you're talking about. The original report of the FBI's confirmation appears to be this SF Chronicle article: https://www.sfchronicle.com/crime/article/Zodiac-340-cypher-cracked-by-code-expert-51-years-15794943.php https://www.sfchronicle.com/crime/article/Zodiac-340-cypher-...