Gyllenhaal, Downey Jr. Sign On For Serial-Killer Thriller

Based on real events, 'Zodiac' will be directed by David Fincher ('Fight Club').

A film about a real-life serial killer who racked up 37 victims, and whose reign of terror consumed the citizens of San Francisco during much of the 1960s and 1970s — a bloodthirsty monster who remains a free man even to this day? Sounds like a job for director David Fincher.

The edgy visionary behind "Fight Club" and "Seven" will helm "Zodiac," according to The Hollywood Reporter, marking the director's first film since 2002's "Panic Room."

The feature, which could see release as soon as late 2006, will star Jake Gyllenhaal of "Donnie Darko" fame and Robert Downey Jr. — who, thanks to his role in "Gothika," is no stranger to the thriller genre — as Robert Graysmith and Paul Avery, two San Francisco Chronicle reporters who investigated the murders. The daily paper was used by the Zodiac Killer as a means of communicating with the city's homicide detectives over the course of 25 years.

"Zodiac," which will be co-financed by Warner Bros. Pictures and Paramount, is based on two books Graysmith penned about the infamous, unsolved-to-this-day case, "Zodiac" and its 2000 sequel, "Zodiac Unmasked: The Identity of America's Most Elusive Serial Killer Revealed."

Mark Ruffalo ("Collateral," "Eternal Sunshine of the Spotless Mind") is in negotiations to play the lead investigator in charge of the Zodiac Killer case.

Downey Jr. will also star in director George Clooney's sophomore feature, "Good Night, and Good Luck" as well as the comedic mystery "Kiss, Kiss, Bang, Bang." Gyllenhaal can be seen in the upcoming movie "Jarhead," the Sam Mendes-led project about a U.S. Marine's experiences in the first Gulf War. He'll also appear alongside Anthony Hopkins and Gwyneth Paltrow in the big-screen adaptation of "Proof," a play about a mathematical genius and his daughter.

Ruffalo plays an architect who falls in love with the ghost of his apartment's previous tenant in the forthcoming "Just Like Heaven," and just wrapped up Rob Reiner's "Rumor Has It," which stars Jennifer Aniston as a woman who discovers her family was the inspiration behind "The Graduate."

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