Few things are more baffling and self-defeating than confessing to a crime you didn't commit. Yet it's remarkably common. It's also intriguing and disturbing how they come about.
A study published in the Stanford Law Review found nearly 20 per cent of wrongful convictions overturned by DNA evidence involved false confessions or self-incriminating testimony. The Innocence Project in the US cites a figure of 25 per cent.
But we don't have to go overseas to find examples. Teina Pora put his hand up to being present at the rape and killing of Susan Burdett; a crime it appears he had no involvement with. The case of Michael October will soon be another.
The issue of false confessions has become a topic of water cooler discussion recently due to the documentary series Making a Murderer. In that, Brendan Dassey, a young, slow-speaking lad, confessed to undertaking a horrific rape and murder with his uncle.
Yet evidence for his version of events appears (based on the documentary, at least) non-existent. He said the victim was chained to the bed, but there were no markings on it. He said she was stabbed and had her throat cut, but there was no DNA evidence. No blood. Nothing.
Forensic testing meant police knew the victim had been shot in the head and they desperately wanted him to say this detail. It hadn't been made public and only the killers could know it. When police probed that it was something to do with her head he paused and said they'd cut off her hair. There was no hair found either.
Watching the police interviews you can almost see the stories being plucked from a young man's cotton wool mind. When his mother asked where the details came from, he said "I guessed". Pushed further he explained, "That's what I do with my homework, too." It is a conversation that distils his childlike naivety and lays it bare.
After confessing, Dassey believed the police would drop him back to school. Instead he went to jail where he remains some ten years later.
Teina Pora, with an IQ of between 74 and 83 and a mental age of 9 or 10, was similar. Both young men were entirely unaware that their words were leading them to prison.
But having a diminished intellectual capacity is not the only reason false confessions happen.
A case with the New Zealand Public Interest Project involves Michael October. Police told October that he was at the scene of a brutal rape and murder in Christchurch in 1994. October believed them and, because he had no memory due to alcohol and drugs, he invented a story putting him there; a behaviour called confabulation.
Neither Dassey, Pora nor October had lawyers while being interrogated. All were interviewed for hours on end. Teina Pora was interviewed for days.
The key element to many such cases is police interviewing procedures. These have been put under the spotlight in the US; particularly the Reid Technique. Reid is a nine-stage interview method that is highly effective at gaining confessions.
But numerous cases and experiments have shown Reid-type interviews to be coercive and far too likely to produce false confessions, especially among youth.
Step six, for example, ends with: "if the suspect cries at this point, infer guilt", which ignores the idea that being accused of committing a horrific crime may produce tears in some people.
In 2012, a Canadian judge concluded that the "Reid Technique is a guilt-presumptive, confrontational, psychologically manipulative procedure".
Reid has been banned for use on youth suspects in several European jurisdictions.
In recent years, the New Zealand police have adopted a British interrogation method called PEACE, which is far less coercive. This bodes well, but the issue of false confessions will push deep into the Kiwi consciousness as the Michael October appeal proceeds.
October once said he did it. The two men who actually committed the rape and murder say otherwise.
Dr Jarrod Gilbert is a sociologist at the University of Canterbury and the lead researcher at Independent Research Solutions. He is an award-winning writer who specialises in research with practical applications.