This case is a real killer

Director David Fincher ("Se7en," "Fight Club") errs on the side of diligence in chronicling the pursuit of the real-life serial killer who terrorized California from the late 1960s through the 1970s. First-rate cast is led by Jake Gyllenhaal as a political cartoonist-turned-obsessive investigative reporter. Also with Robert Downey Jr. Mark Ruffalo, Anthony Edwards, Brian Cox and Chloe Sevigny. 2:36 (violence, vulgarities, drug use and sexual images). At area theaters.

One of G.K. Chesterton's Father Brown stories submits this aphorism for your approval: "The criminal is the creative artist, the detective, only the critic."

It often seems that the fascination with serial killers springs not only from a morbid interest in wanton evil, but from the notion of someone going outside conventional boundaries to carry out his deepest obsessions; the kind of person who, under different circumstances, might write songs or paint masterpieces that galvanize the world.

"Zodiac" grapples with the intriguing premise that even those "critics" investigating serial killers can bend themselves into a kind of obsessiveness that may be as loopy - or as insidiously inspired - as their quarry. It takes its title from the real-life mass murderer who spooked Northern California in the later 1960s and early 1970s - and, for all anyone knows, may still be at large.

At the center of this story is Robert Graysmith (Jake Gyllenhaal), a political cartoonist for the San Francisco Chronicle, who was swept up in the case when his paper and others in the region became vehicles for the Zodiac Killer's boasts, threats and anagrams.

Graysmith at first hovered on the periphery of the investigation, whose principal figures were homicide detectives Dave Toschi (Mark Ruffalo) and William Armstrong (Anthony Edwards), along with Chronicle crime reporter Paul Avery (Robert Downey Jr.). Each of these idiosyncratic men were, in a way, as much the Zodiac Killer's victims as the five people he was known to have killed, the two he wounded and the dozens of others he claimed to have murdered.

The years of false leads eventually wore out the dogged Armstrong while Toschi, whose swagger was said to have inspired both "Bullitt" and "Dirty Harry," eventually lost his credibility. Avery, played with characteristic electricity by Downey, stumbles into career-ending drug addiction and alcoholism. This left Graysmith, who is seemingly unencumbered by quirks and bad habits, but nonetheless gets so wrapped up in the case that he imperils his marriage - and, it's implied, his life.

Director David Fincher ratchets down his customary showiness in favor of conscientious realism. His dedication to nailing down facts, personalities and period detail doesn't keep you from getting the willies, especially in his reconstruction of the murders.

But Fincher gets so caught up in the particulars of the story that, as with his protagonists, he loses his momentum, getting tangled up in a thicket of red herrings and false leads that make this 2 1/2-hour-plus movie feel even longer. Not even the energy level of his cast - which includes the indefatigable Brian Cox doing superstar attorney Melvin Belli to a high gloss - can sustain the static pace. And can one say, for emphasis, how much Downey is missed as soon as his character no longer is involved in the hunt?

Still, it's just such chaos that gives "Zodiac" its own brand of perverse fascination. Overall, the movie's a sprawling mess. But its twitchier particulars dare you to hold them up for further, if cautious, scrutiny.