Arthur Leigh Allen did it.
From the silence of the lambs:
From Silence of the Lambs
Hannibal Lecter: First principles, Clarice. Simplicity. Read Marcus Aurelius. Of each particular thing ask: what is it in itself? What is its nature? What does he do, this man you seek?
Clarice Starling: He kills women...
Hannibal Lecter: No. That is incidental. What is the first and principal thing he does? What needs does he serve by killing?
Clarice Starling: Anger, um, social acceptance, and, huh, sexual frustrations, sir...
Hannibal Lecter: No! He covets. That is his nature. And how do we begin to covet, Clarice? Do we seek out things to covet? Make an effort to answer now.
Clarice Starling: No. We just...
Hannibal Lecter: No. We begin by coveting what we see every day. Don't you feel eyes moving over your body, Clarice? And don't your eyes seek out the things you want?
I know its a movie but it makes alot of sense.
Arthur Leigh Allen lived right near Darlenes job. He probably saw her all the time and became obsessed with her. She was his first. Its simple. Arthur Leigh Allen did it. The other evidence - or lack of - doesnt matter . The rest of the evidence against him DOES.He was smart enough to keep not leave clue behind. He cleaned out his place of evidence. Allen might ahve been a sick pedophile- but he wasnt STUPID. Its over. Zodiac is dead and rotting in hell.
Ive seen alot of people who want to believe believe he got away with it( unsub this- unsub that)- but he didnt. he died long ago and was about to be indicted by Mageaus ID.
Merry Xmas to all ( and to hell with everyone else who doesn't believe)