Stuff Circuit investigates the hidden life and crimes of Joanne Harrison - aka Joanne Sharp - a million-dollar conwoman whose previous offending was secret when she ripped off taxpayers.

For a fraudster who pocketed more than $1 million of other people's money, Joanne Harrison had modest tastes.

She had no gambling or drug habits, and much of what she stole went towards that most mundane and Kiwi of expenses – paying off the mortgage.

But a fraudster isn't a fraudster without a flash of ostentatiousness, a giveaway.

And for Harrison, who would eventually find the fame she never sought as the woman who ripped off the Ministry of Transport, the first flash was a Range Rover.

* WATCH: The Fraudster: Life and Crimes of a Conwoman

"I was down in the car park... one day and Joanne drove in – nearly run me over, I think – in a flash Range Rover," says Mike Keaney. "I knew then, I knew immediately – every part of my being knew – there was something really wrong here."

Keaney was right, and Harrison was soon brought to justice.

Except, this incident was not when Harrison was at the Ministry of Transport. It was a decade earlier, in 2007, and Harrison was not known as Harrison. She was using the name Joanne Sharp.

A Stuff Circuit documentary, The Fraudster, has revealed the life and crimes of Joanne Harrison, aka Joanne Sharp, aka Joanne Sidebottom. Her Transport Ministry fraud became front page news in 2017, but what couldn't be reported at the time because of a suppression order was the extent of her crimes.

But after having the suppression order lifted, Stuff Circuit can finally reveal her criminal history, and how she charmed her way through corporate and government jobs in New Zealand and Australia, leaving a trail of carnage and duped senior executives, shaking their heads at the fact they'd been taken in.

All of them were left ruing the day they met her.

"The effect that person has had on my life and that of my family is almost beyond explanation," says her most high-profile "victim", former Transport Ministry chief executive Martin Matthews.

"I was the person who brought her to justice. She went to prison because I did the right thing. Somehow I think Heather, my wife, and I have ended up paying a much bigger price than the criminal for doing the right thing."

The documentary reveals details of Harrison's time at Tower Corporation in the mid-2000s – her Range Rover days.

In fact, the car was an example of how she operated. She hadn't bought it with her own – albeit ill-gotten – money.

SUPPLIED Joanne Harrison was general manager of organisational development at the Ministry of Transport.

Rather, she had manipulated the corporate system at Tower so that as part of her remuneration package her company car was the flashiest in the carpark – the carpark where she encountered Keaney, a private investigator who did insurance fraud work for the company.

In another of her cons, she tricked the company into paying her a $35,000 relocation fee twice by falsifying the company's copy of her employment agreement.

"It's consistent with Joanne's sheer dishonesty," says Keaney. "And using and fiddling with documents is a great MO (method of operation) for fraudsters."

Harrison – or Sharp, as she was known then – was paid a relocation fee because she had come to work at Tower in New Zealand from England, armed with glowing references from her previous employer.

CHRIS SKELTON/STUFF Joanne Harrison during sentencing at the Manukau District Court, Auckland.

But documents obtained by Stuff Circuit under the Official Information Act reveal Harrison had lied her way into the country, providing "fraudulent, false or misleading" information in her visa application.

Immigration New Zealand records show she obtained residency under the Skilled Migrant Category after submitting two references from her UK employer, HSBC.

But one of the reference writers no longer worked for HSBC, and there are doubts as to who the second referee even was.

In any case, neither was authorised to provide a reference on behalf of the company.

Harrison's CV also contained lies about what roles she held at the company.

Harrison later used HSBC references as proof of her good character when she appeared in court over the Tower fraud. The charges she faced amounted to $110,000 – which she paid back – but as some of the charges were representative, sources said the figure was at least $300,000.

The judge in the Tower case sentenced her to 300 hours' community service, and gave her permanent name suppression, convinced "the possibility of reoffending is in no way on any kind of cards".

Under cover of the court's suppression order, she landed a job at the Far North District Council, where she changed her name to Harrison, and told more lies about her past before being moved on, the documentary reveals.

From there she went to Australia for a top job at a Victorian state water company – helped in part by more glowing, and fake, references.

The role ended abruptly, with the Victorian police on her tail.

But that didn't stop her manipulating her way into a job at the Ministry of Transport, where she ended up earning a salary of more than $260,000, while stealing $726,000 through an elaborate false-invoicing scheme.

"Nice," says Keaney. "Good take – but that's her MO."

As at Tower, Harrison hardly splurged. Though there were a few trinkets she couldn't resist – a couple of Rolex watches, rings and other jewellery.

After serving time in jail over the ministry fraud, Harrison was deported back to the UK in January.

Former Tower colleague Andrew Hooker has no doubt about what she'll be up to.

"As sure as God made little apples," says Hooker, "she would have reinvented herself and she'll be ripping someone off in England as we speak."

* The Fraudster: Life and Crimes of a Conwoman, a documentary by Stuff Circuit, funded by NZ on Air, is available on Stuff now, and screens tonight on Māori Television at 7.30pm.