When I was a kid, I read People magazine. I mean read it. As in every week. A couple of years into my subscription, I could name the husbands of Elizabeth Taylor, the number of cars owned by Jay Leno, the blood-type of every member of the house of Windsor. Weirdly, People also taught me a lot about serial killers.This was during the era of Jeffrey Dahmer and Hannibal Lecter, and in between its celebrity puff pieces and heartwarming tales of uplift, People lingered voyeuristically over every lurid detail of every serial killing, real or imaginary, from Florida to Alaska. Even now the names are coming back to me. Ted Bundy. Aileen Wuornos. You know: People. Especially compelling, for a ten-year-old (and, apparently, for everyone else who read People) was any whiff of weird sex. Of course, from a ten-year-old’s point of view, all sex is weird sex. As all violence and loneliness and pathology seem obscurely familiar. But anyway, I gobbled this serial-killer stuff up like Halloween candy, though I knew I shouldn’t. And, as with the candy I’d stashed throughout my room, my People binges would leave me feeling sick to my stomach and rotten inside.I was doing a pretty good job repressing this, my brief and shameful fascination with serial killers, until last week, when I read Robert Graysmith’s Zodiac Unmasked. I had just seen David Fincher’s scrupulous movie about the Zodiac killer who terrorized Northern California in the early 70s. My engagement with this movie was (I thought) deep, thoughtful, moral… not at all voyeuristic or creepy or weird. Then on the way home I had to go and buy Graysmith’s book, one of the sources for the movie. I read 450 pages in just over 24 hours.I cannot with any confidence say that this is not the worst book I’ve ever read. Line by line, paragraph by paragraph, Robert Graysmith’s sequel to his bestselling Zodiac is itself a crime-scene: missing transitions, felony-grade solecisms, metaphors even more overwrought than this one, interspersed with anxious self-congratulation. It is the anti-In Cold Blood. Which makes it all the more mysterious that I couldn’t put it down.One explanation is that Graysmith essentially turns the killings into a dime detective novel, gaming the material for suspense.Another possible explanation lies in all the ways the Zodiac killings do not resemble detective novels. The clues do not line up to point in a single direction (despite Graysmith’s best efforts). Every pattern is broken. The puzzle-solving part of the mind, frustrated, cannot let go of the crime, even if the moral sense longs to. Thus we run over the facts again and again, hoping that this time, they will yield some proof and we can relax again.The brilliance of Fincher’s movie is that it dramatizes this compulsion onscreen. Jake Gyllenhaal, as cartoonist-cum-gumshoe Graysmith, offers an objective portrait of our corrosive fascination with violence. In the grip of his obsession, he resembles a ten-year old (which may explain why Graysmith writes like one). In the book, by contrast, the real Graysmith effaces himself; we are left to feel the sickly fascination ourselves. Maybe this is the more honest approach. Still, I prefer the clinical lens to the pornographic one. Fincher himself, in a couple of early scenes (as in much of his earlier work), stoops to aestheticism. But if a distressingly well-crafted murder scene lowers a veil between the audience and the victim, what can we say about a sentence like “Only the most extreme adversity could prevent this prophet of death from gloating over the proliferation of his obscene word?”Ultimately, the movie Zodiac felt more like an adaptation of Norman Mailer’s The Executioner’s Song than of Graysmith’s Zodiac writings. Like Mailer, Fincher is interested in murder as a window into human nature. And like Mailer, Fincher is as interested in the traumatized bystanders as he is in his killer. It may not be easy, watching Zodiac or reading The Executioner’s Song, to get over the creepy feeling of being compelled by the suffering of others. But at least these made me think about that feeling. Zodiac Unmasked just let me feel it.