Why I feel like Zodiac isn't BTK:
I feel like the profile for BTK and Zodiac don't match- BTK was too involved with his victims for me. Also, Zodiac showed a clear escalation in his MO, so it wasn't like the lover's lane shootings were his trial run. If it was, and he was BTK, there would have been more signs of sexual experimentation and escalation- even if it started after the first kill. He wouldn't have stopped on his own. Also, he wouldn't have changed MO's and continued active through 1991 killing differently. A killer like Zodiac is too methodical and driven by fantasy to switch from lover's lane shootings to BTK's M.O.
Why I feel like Zodiac could be the Phantom Killer:
They have the same MO. The Phantom killings were at the perfect time to be Zodiac's trial run while away from home so the murders would not get traced to him. Also, they are convinced the Phantom killer had to be an outsider who didn't live in town because it was a tight-knit community. Also, the Phantom killer was obviously motivated and wanted to continue killing, but he stopped after a year despite there being no arrests (besides Youell Swinney, who obviously didn't do it). He would have continued if he was in the same place. Some people discredit this theory because the Texarkana Phantom killer interacted with his victims sexually. This was only in one of his early attacks and if the events did not fit his fantasy and help him to achieve a release he would have tried a new method after having a cooling-off period. An example of a new method of release could be continuing lover's lane killings but getting off instead by TAUNTING THE COPS. Also, the Zodiac couldn't have been a copycat of the Phantom Killer, he had too much of an ego not to develop his own MO and a copycat would have been too devoted to the Phantom Killer to "upstage" him by adding ciphers and trophies from previous victims.
Here's my idea of a timeline:
1946: goes to stay with family in Texarkana.
1947: returns home and has a cooling-off period
1950's: tries to suppress his urges in order to have a normal young-adult life but his fantasies become too strong, the people around him probably noticed he became more withdrawn and obsessive-he is now living a double life. This double life isn't hard for him because he is smart but reclusive and very private. People around him might think he is a little quirky or weird, but he appears nonthreatening. He begins to adjust his killing method to fit his surroundings and develops a code for his ciphers.
1960's: Zodiac killings
1970's: stops for who knows what reason (I haven't figured that part out yet lol)
keep digging guys!!
xo