Amy Bock was a criminal "supreme in her cleverness". Her most famous con saw her pose as a man for 15 weeks and marry the daughter of her landlord. Nobody has ever been able to explain what motivated her lifetime of fraud and scams.

Detective Henry Hunt knocks on the door of Percy Redwood, a wealthy sheep farmer on an extended holiday at Nugget Point on the Catlins Coast.

Over the last few months, Percy had made a lot of friends in town, in fact, he just recently married a local woman called Agnes Ottaway.

The door opens. Percy, a very short man, told his friends he used to be a jockey in his younger days. But that was a lie, pretty much everything Percy told his friends was a lie.

"The game is up, Amy," said Detective Hunt.

Percy's shoulders slump. "I see you know it all," he said... or rather, she said.

Percy was not really a wealthy sheep farmer and former jockey. He was a persona invented by Amy Bock, the most prolific con-artist in New Zealand history.

"A Woman Bridegroom, Exploits Of An Adventuress, An Extraordinary Story"

"In Man's Attire, A Woman's Escapade"

"A Marvellous Masquerade, A Woman Dressed As A Man Marries A Port Molyneax Girl."

"The Champion Crook of the Century"

This is just a small sample of the scandalised headlines which filled the national newspapers after Amy's scam was revealed. The papers delved into her old court records, they interviewed her childhood friends and trawled through older newspaper clippings.

What they uncover is a lifetime of scams, frauds and lies going all the way back to Amy's childhood in the rural Australian town of Sale, a few hundred kilometres east of Melbourne.

"It's In My Blood"

Amy came from a respectable family in Sale, her father ran a successful photography business which helped him make connections with the movers and shakers in town.

But there was a tragedy at the heart of the Bock family. Amy's mother suffered from a serious mental illness.

" would have very manic episodes and then episodes of melancholia. So probably what we would think of now as manic-depressive ," said Dr Jenny Coleman, author of Mad or Bad: the life and exploits of Amy Bock.

When Amy was ten years old her mother was locked up in a lunatic asylum. Amy never saw her again. She died three years later.

It was around this point people started to have concerns about Amy's mental health. She began telling stories and acting out in bizarre ways. One time she bought a load of books under her father's name and just gave them away to random people in town…

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