According to Variety, Anthony Edwards has joined the cast of Paramount and Warner Bros.' serial-killer thriller Zodiac, to be helmed by David Fincher.

Edwards, a four-time Emmy nominee for his work on "ER," will portray the partner of the lead police investigator on the case, played by Mark Ruffalo. Edwards' character suffers a nervous breakdown due to the assignment. Robert Downey Jr. and Jake Gyllenhaal also topline.

Edwards most recently starred opposite Julianne Moore in The Forgotten. Other credits include Thunderbirds and Northfork.

Production is slated to start in August, with Phoenix Pictures producing. Scribe Jamie Vanderbilt is adapting from Robert Graysmith's nonfiction tome Zodiac and 2002 sequel "Zodiac Unmasked: The Identity of America's Most Elusive Serial Killer Revealed."

Zodiac was released March 2nd, 2007 and stars Jake Gyllenhaal, Mark Ruffalo, Anthony Edwards, Robert Downey Jr., Brian Cox, John Carroll Lynch, Richmond Arquette, Bob Stephenson. The film is directed by David Fincher.