Cameron says he wasn't out to solve the Black Dahlia, or JonBenét: "I didn’t even pay attention to any of that stuff. It was just following the evidence."

Confirmation bias happens when we ignore evidence that discredits our theory, and over-value evidence that confirms it. The directors of Making a Murderer had a bias – the belief that Steven Avery is innocent – and showed us evidence to support that bias.



John Cameron has a bias. But then, so does this article.

“We are programmed to try to make sense of the world,” psychologist and lecturer Dr Julia Shaw told BuzzFeed, “and confirmation bias and pattern-recognition often work as thinking shortcuts, but they can also get us into a lot of trouble.

“We may be blinded by our biases, and see links where there may not actually be any. If we assume that a single killer is responsible for a number of deaths, we may make the evidence fit our theory, and as a result, fail to look for, and apprehend, the actual killer.”

In Ed Edwards, Cameron has found a real monster, a man capable of extreme depravity who may have committed many more crimes than he was convicted of. But Cameron's years as a detective don’t free him of confirmation bias.

“Police officers generally have the same kinds of assumptions and biases as everyone else,” Dr Shaw says. “Detectives are definitely susceptible to confirmation bias.”

To believe it possible that Ed Edwards killed Teresa Halbach, you’d need to believe that a man was capable of killing constantly for 50 years and not getting caught. You’d also need to believe it’s possible to commit, on average, 10 murders a year without leaving a clue.



You’d need to believe Edwards was behind the most infamous unsolved murders in US history – the Zodiac killings – a claim refuted by Zodiac expert Tom Voigt, who runs zodiackiller.com: "If Edwards was Zodiac, I'll eat my website," Voigt told BuzzFeed. (Voigt has his guy, too.)

And you’d need to believe that Edwards, for a short period of time, decided to wear a hood and tabard, and paused his regular penmanship to write cryptic notes in a glyph code of his own devising.

Finally, you'd need to believe that a man who confessed to committing crimes for the recognition would have gone to such great lengths to avoid getting any.

John Cameron believes. He has his Zodiac. He also has his Moby Dick and his Moriarty. There is no doubt Ed Edwards was a murderer, but perhaps one who was more myth than mastermind.

John Cameron has a story to tell, and it’s a hell of a story.

But maybe it's just that, a story.



