Hi , 
I am studying the letters of the zodiac, observing things like size, idiosyncrasies, dates, stamps etc.
In this case, I don’t even know if it is a real letter from the zodiac, because, we don’t even know (with certainty) that the crime committed against Bates was in fact the work of the infamous criminal.
https://en.wikisource.org/wiki/Zodiac_Killer_letter,_April_30th_1967
Likewise, there is no way to say that the "risk" below is in fact the letter Z.
BATESHADTODIETHER
EWILLBEMOREZODIAC
BATESHADTODIETHER EWILLBEMOREZODIAC
I noticed that, replacing the "Z" with a zodiac word, the message, without space, is 34 in length and can be divided into 2 lines of 17. Does that mean anything ?? I don’t have it, because as I said, we don’t even know who the author of the letter was.
Marcelo 
PS: Notice who the "Z" is on the twenty-sixth line of the lined paper (position of the letter Z in the alphabet). Someone must have already noticed this.
https://zodiacode1933.blogspot.com/
OK this is again creeping me out as I recall a day on the beach at Corona del Mar, Ca when my boyfriend asked me to write some things for him. We had been discussing movies we’d seen; one was "Psycho" and talking about the Bates Motel!
I remember trying to disguise my writing and printed (perhaps with left-hand) since he was being so mysterious re. why he wanted me to do this for him! It was one of those mysterious but innocuous things he did as I have posted about extensively here!
We were sitting on the beach and had been discussing movies we’d seen. One was "Psycho" and the Bates Motel with the famous shower scene. I don’t think the part about Bates Had to Die was requested but could have been. If so, I would have thought it was strictly in reference to this movie!
In other words, the last sentence could have been written by me at the request of my boyfriend (poi) about whom I have posted here extensively for approx. 11 years now in hope the real Zodiac would be found and it would not be him!
I would be more than happy to provide any further information to any offical investigator btw. If my fingerprints or dna were to be found on this or the others I remember, that would be enough proof in my mind to confirm my worst suspicions.
I must add here I notice the date here is April 30, 1967 so that makes it IMPOSSIBLE for that to have been my writing and again relieves all anxiety aboutmy boyfriend because we did not meet each other UNTIL 1970 and it was June as best I can recall.
Some of the other letters cause the same confusion re. dates as the Riverside also as I remember the details re. him asking me to match the printing on the envelope that he said he’d done and write "attn:crime" but by then, he’d moved from Corona del Mar to an apt. at MacArthur Village in Newport Beach and it was approx. 1973. So the dates of the postmarks do not match.
This is one reason why I would very much like to see all the undisclosed evidence as I wonder if there are other letters like these there!
