[Valpal1]

I always wondered if Zodiac was some tool falsely claiming responsibility and sending his notes and codes to police and media for giggles.

Meanwhile, the actual serial killer(s) appreciate the diversion.

[Boogieman]

Some of the letters were definitely known to be fakes, but many of the letters are absolutely genuine.

For one, there was information in the letters that it’s likely only the killer would know. The killer also left writing at one of the crime scenes in handwriting that matched the letters closely. Finally, the killer included physical evidence from one crime (a piece of a victim’s bloody shirt) in one letter to give solid confirmation that he was the killer.

[circlecity]

“I always wondered if Zodiac was some tool falsely claiming responsibility and sending his notes and codes to police and media for giggles.”

in one of his letters he sent a piece of the shirt the cab driver he murdered was wearing. Other letters contained facts of the murders which had never been made public. So, it was definitely him.