The Mr Big technique is a powerful tool used to get criminals to confess. But is it fair? Is it just? Or does it lead to false convictions?

Can the police use a story to get to the truth about a murder?

In 2014, David Lyttle, a struggling builder in the little town of Halcombe, answers a knock at his door. What happens then leads him into a shadowy criminal organisation that offers him friendship, a new job, and riches, in exchange for one thing: honesty.

Pressed by the organisation's boss, David Lyttle confesses to murdering his friend Brett Hall three years earlier. He shows the boss where he buried the body parts. Then, his world explodes. He's arrested and charged with murder. The whole thing was a police sting operation known as "Mr Big". And now David has confessed.

Or has he?

The body parts aren't there. It starts to look like the confession doesn't add up.

How reliable is a confession obtained by dangling these prizes, and where it costs the suspect nothing to make up a story the boss apparently wants to hear?

And how good are we - and are jurors - at working out whether to believe such a confession?

This series follows the prosecution of David Lyttle through to the verdict and its aftermath. We visit the campsite in rugged bushland 30 km from Whanganui where David was building a house for his best friend Brett Hall. We learn that Brett was annoyed at David and believed David was ripping him off. We also find out that Brett was dealing drugs and told people he had a big deal coming up soon. Then he disappeared.

Did Brett fatally fall out with David over a building dispute? Or was he murdered over a drug debt?

The trial looks to be an uphill battle for David Lyttle. There's the confession evidence. The problem that juries almost always convict Mr Big defendants. And the fact that, in order to show the jury how powerful the manipulation was so that they might understand how he came to give a false confession, David is going to have to convince them that he's a liar, a dupe and a willing criminal.

Journalist and lawyer Steven Price looks into the stories and failings of one of Aotearoa's most controversial 'Mr Big' investigations. Mr Lyttle meets Mr Big looks at the evidence pointing to David, and the evidence pointing to a drug killing. We examine the police's astonishing failures to properly disclose evidence to the defence - even when that evidence pointed to another killer. We follow the ups and downs of the trial…

Go to this episode on rnz.co.nz for more details