Likewise. I find books/movies/songs about serial killers fascinating. I myself have been obsessed about the Zodiac killer for years. And I mean before the film came out. Which leads me to my next point.
I think the most successful ones are the ones that get away. After decades, countless suspects across California and DNA testing (even on exhumed corpses) the Zodiac has never been caught. I have my favourite suspect, Arthur Leigh Allen, but a lot of evidence has ruled him out.
The way the letters "coincidentally" stopped when he was in prison and started back after his release, the way he wore a zodiac watch, the fact that he can be placed near the scene of just about every murder. For example, the Zodiac killed someone in Fresno, where was Allen? Fresno. San Francisco, where was Allen? San Francisco. I have no doubt that he was involved to some extent. What I don't know is whether he was the only one. If he wasn't, did he cooperate with someone or was there an unaffiliated copycat?
He was also discounted on his handwriting, although people close to him claimed he was ambidextrous.
The case is still being investigated today, although it is on the back burner. Allen's body was exhumed to test for dna evidence on an envelope that one of the Zodiac's letters were sent in. It didn't match his DNA. But is it that unlikely that a serial killer may hand a letter to someone and ask them to lick the envelope?
Edit: Before getting back on topic, here is one of my favourite songs.
<a href="http://www.youtube.com/watch?v=YnvE_UGOf94">YouTube Link</a>