When The Movies Get It Right: Probable Cause and David Fincher's Zodiac

[Originally published June 1,  2013. Since today is the 10th Anniversary of the release of this classic crime film, I'm re-upping it. Enjoy!]

When Dirty Harry opened in 1971, it became a box office success and critical darling. It solidified Clint Eastwood's rising star and proved that gritty cop dramas like Bullitt, and The French Connection were legitimate sources of entertainment to a world that grew tired of psychedelic, experimental, 60s era musicals and comedies. The film was very loosely based on the real life (and in 1971, still ongoing) Zodiac murders; likewise, Eastwood's character was based on the police officer assigned to track down the Zodiac, San Francisco Police Inspector David Toschi. Dirty Harry ends with Harry Callahan getting the drop on the film's villain, Scorpio, in a San Francisco junkyard where Eastwood delivers his famous "do you feel lucky" speech. Then he blows Scorpio away with his .357 magnum revolver... a gun so powerful it can carve a hole in solid concrete. Of course the real Zodiac never got to be on the receiving end of such rough justice and Dave Toschi retired in 1983 having never arrested the most famous unknown serial killer in American history.

Dirty Harry has many charms: an iconic antihero, one of the great movie quotes of all time, topical relevancy, and a well-staged, taughtly paced finale. But it was a hit precisely because it allowed the American public to get closure on a national terror that would never resolve. For that same reason, the film left me cold. As you already know, I'm a big supporter of verisimilitude in film. I don't believe that filmmakers need to sacrifice reality on the alter of drama. And while I understand why the filmmakers of Dirty Harry killed off Scorpio, I don't have to tell you that gunning down the bad guy - even if he deserves it - is pretty shoddy police work.

That's why David Fincher's epic crime film Zodiac - a richly detailed chronicle of the Zodiac case - is one of my all-time favorite films. It understands to its very core what good police work is and how good policemen investigate crimes. About halfway through the film, Toschi (played in a career-making turn by Mark Ruffalo), exits a policeman's only screening of Dirty Harry, after years of being stymied in his investigation. Toschi is so torn up about his inability to catch the Zodiac and the movie's unabashed twisting of the truth that he can't watch the whole thing... he just paces and smokes in the lobby. When the movie lets out, the police commissioner approaches him and says, "Dave, that Harry Callahan did a hell of a job closing your case!"

Toschi's response: "Yeah, no need for due process, right?" Zing!

You see, everyone gets due process in this country. Everyone. Regardless of age, race, gender, sexual orientation, national origin, ethnicity, class, or any other category you can devise. Killers, rapists, thieves, and bad men all still get due process because it's written in the Constitution, the highest law of the land. Due process can mean a lot of things, but in the context of a criminal case, it means that you can't be punished without a fair trial and a proper investigation. And to conduct a proper investigation, police need to investigate clues, gather evidence, and then make arrests based on that evidence. That evidence, if properly gathered, catalogued, and analyzed, results in Probable Cause, a foundational element of criminal investigations that allows an officer to make an arrest based on that evidence. You can't make an arrest without Probable Cause and if you do, the suspect will be freed before you can say "kicked off the force."

To drive that point home, Zodiac shows Toschi and his partner Bill Armstrong investigating Arthur Leigh Allen, a very promising candidate for the Zodiac. Allen had been implicated by a former coworker for saying things that later showed up in the Zodiac letters. Allen had the same glove size, boot size, and general appearance as the Zodiac. He owned the same types of guns, had the same military training, lived nearby one of the Zodiac victims, and even owned a Zodiac brand watch with the infamous crosshairs insignia that the Zodiac killer signed his letters with. But despite eliciting high interest from the police, Allen was never arrested. How can that be, you might ask? Because even though there was an abundance of evidence, it was all circumstantial - in other words, the evidence was  highly inconclusive, no matter how suggestive it was of Allen's guilt. In order to justify a probable cause arrest that would stand up to judicial scrutiny (i.e. not get thrown out of court), they needed something much more concrete to tie Allen to the Zodiac killings. That's why the film kept harping on DNA and handwriting samples (the Zodiac hand wrote nearly all of his letters). And when they got both from Allen, they didn't match the Zodiac.  The film takes great pains to show us Toschi and Armstrong gathering evidence, going through the motions of getting a search warrant to Allen's house. They fail because, according to proper 4th Amendment procedures, the evidence to get a search warrant issued had to be based on probable cause, which the issuing judge didn't believe existed. They do finally get the warrant when Allen moves to a different jurisdiction with a judge who is willing to issue the warrant. The scene where they toss Allen's trailer is one of the creepiest scenes in the film.

Toschi and Armstrong believed in Allen's guilt to such a degree that when they're told that Allen's handwriting isn't a match for the Zodiac, they're visibly destroyed. Toschi's career takes a nosedive (at one point, he's suspended from the force after being implicated in the news as the writer of some of the Zodiac letters. He was later exonerated) and Armstrong transfers out of the department. Without the handwriting match, they don't have probable cause, and without probable cause, there's no arrest, and without the arrest, they can't investigate Allen further. The case hits a dead-end. And rightfully so. Allen may have been the killer, but there just wasn't enough evidence to get him in front of a judge.

Do you know what Toschi and Armstrong didn't do? They didn't follow Allen against their Captain's orders. They didn't bug his phone without a warrant. They didn't catch him in the act and gun him down after a dramatic chase.

One of the things that makes Zodiac a great film is that it eschews a lot of the easy choices that screenwriters make when adapting from real events. Often, screenwriters will eliminate, compress, or invent characters and events to suit the narrative structure rather than be truthful to reality. But that didn't happen with Zodiac. The film takes time to explain what probable cause is, why it's important, and why Toschi's and Armstrong's case against Allen dies on the vine without it. Later in the film, when cartoonist Robert Graysmith picks up the investigation on his own, he's instructed by various law enforcement officials, including Toschi, to stay away from the circumstantial evidence and stick with the DNA and handwriting samples because they're concrete and will hold up in court. The rest is just window dressing.

The film treats police procedure with respect, it treats cops and their investigative methods with respect. It doesn't take the easy way out, and it knows that you can still build drama and tension without twisting reality. More than that, it understands why due process is important and why, sometimes, you have to let the bad guy go if you want to honor the Constitution.

Greg Kanaan

The [Legal] Artist, Boston, MA, USA