"The most vile criminal ever to be tried in New Zealand" Thomas Hall's crimes scandalised New Zealand when it was revealed he had attempted to murder his wife in order to steal her family fortune.

"You have achieved in the annals of crime the position of being the vilest criminal ever tried in New Zealand."

That's what the judge said to Thomas Hall as he sentenced him to life in prison in 1886.

Tom Hall was part of a rich and influential family in Timaru. His uncle, Sir John Hall, was a former Premier of New Zealand. You can imagine the scandal when news broke that a member of that family had attempted to poison his wife in an effort to steal her family fortune.

But while the initial reaction was a sort of morbid glee, it quickly turned to horror when the full extent of Tom's crimes were revealed.

The son of a rich sheep farmer, Tom Hall was born during a gigantic wool boom in the 20 years from 1850 to 1870. That boom saw Timaru grow from a few shacks on the beach to one of the wealthiest places in the country.

Tom initially went into the family business working a sheep run in the Mackenzie Country but quickly abandoned that line of work, due to harsh conditions as revealed in his diary.

"July 20: stayed a night with Parkerson on the way up. Lots of snow and severe frost. My horse had icicles three inches long on his nostrils. Twenty inches of snow fallen. Twelve inches still lying."

Instead, Tom Hall became a businessman... and a con-artist.

"People thought he was good at what he did," says Peter Graham, author of Vile Crimes: the Timaru Poisonings. "No one had any reason to suspect there was anything wrong with company."

Tom's business was in finance, property and insurance, which he used as a cover to steal clients' money and forge documents to get loans from banks.

"He was shuffling money around left, right and centre," Peter Graham says. "He was trying to stave off the day when he was going to be exposed."

A worldwide credit crisis in the 1880s proved disastrous for Tom's scam. With credit drying up he was forced to look elsewhere for money.

"His way out was to marry a wife with money," Peter says. "He picked upon Kitty Cain. She was one of two stepdaughters of Captain Cain really a founding father of Timaru."

But it wasn't enough to simply marry a rich woman, Tom wanted Kitty's money all to himself. Even before they were wed, he was planning on killing her.

"Tom Hall travelled to Christchurch to get legal advice before he married Kitty," says Peter…

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