The Channel 9 letter contained all the ingredients related to the map below. The letter threatened to kill Susan Atkins calling her the "Judas of the Manson Family" and threatening "Shes gona get hers now". She was present at 10050 Cielo Drive during the murder of Sharon Tate. The letter continued with "Hey - - - you actors - this is your lucky Break. Remember - whoever plays me has his work cut out for him". Unsurprising rhetoric from the Zodiac Killer (or copycat), bearing in mind the location of 5515 Melrose Avenue by Paramount Studios and the Hollywood Hills.
The author of the envelope wrote the reversed 1234567 A.G.C.G.T.H. (All Good Children Go To Heaven) on the envelope, taken from The Beatles You Never Give Me Your Money lyrics, as well as drawing the Apple logo from their record label in the bottom left corner. This was also written in blood on a door at the Manson Family Spahn Ranch at 12,000 Santa Susana Pass Road in the Simi Hills. Boxed off in the top left corner of the envelope, usually reserved for the sender's return address, were the reversed letters AIC. Bearing in mind the Zodiac Killer was active in California, and the Channel 9 envelope was postmarked Anaheim, California, the Zodiac Killer was probably telling us his return address was "ANAHEIM IN CALIFORNIA".