In Graysmith's second book (ugh), pg 176 "Old Tom" is mentioned by Toschi.
Toschi states he has an entire file of Old Tom's "bogus" Zodiac letters. Toschi supposedly stated "he's playing games again".
Graysmith stated he met with Old Tom and that he was "totally obsessed" with the case.
Anyone know anything more about this? I wonder what letters were faked. He does mention typing...not that all of the fakes were typed, but it appears as some were.