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

Staff at a former employer of a public servant sacked for alleged theft say concerns were previously raised about her.

Joanne Harrison, a senior manager at the Ministry of Transport, was sacked last week for allegedly stealing hundreds of thousands of taxpayers' dollars.

She's understood to have left New Zealand, possibly for Canada, after being accused of stealing money through false contracting arrangements.

PHIL REID/FAIRFAX NZ Ministry of Transport chief executive Peter Mersi. He said staff felt let down and betrayed by Harrison.

Ministry management was alerted to "financial discrepancies" linked to Harrison, who was the Ministry's general manager of organisational development, earlier this year.

Those discrepancies amounted to a "six-figure fraud", understood to be about $750,000 to $1 million.

The Serious Fraud Office was called in, and concluded its investigation a week ago, a source said. Harrison was sacked shortly afterwards.

MEGAN HUNT/ FAIRFAX NZ Labour transport spokeswoman Sue Moroney urged Transport Minister Simon Bridges to "come clean" about what he knew of the case.

The Serious Fraud Office has confirmed an investigation at the ministry is under way.

NEW TRANSPORT CEO: 'STAFF FEEL BETRAYED'

Ministry of Transport chief executive Peter Mersi​, who took over the top job just four days ago, confirmed Harrison was no longer a ministry employee, "and her whereabouts are a matter for the Serious Fraud Office".

He said staff felt "betrayed" by Harrison.

"My focus is on ensuring this person is held fully to account for her actions, and that any money that may have been misappropriated is recovered.

"In light of what has happened, it is prudent to confirm that our systems, processes and controls are robust. To provide this assurance, a number of reviews are now under way. These focus on internal controls and recruitment processes.

"This was a senior staff member in a position of high trust, and my staff feel incredibly let down and betrayed by her actions."

State Services Commissioner Peter Hughes confirmed his department had been made aware of the alleged fraud and subsequent SFO investigation.

"Mr Mersi is taking this issue extremely seriously, as I would expect of any chief executive," Hughes said.

"The department has been focused on taking appropriate action and I know Mr Mersi is determined to get to the bottom of this urgently, and he has my absolute backing on that."

'A DIFFERENT LEVEL OF CREATIVITY'

Harrison's time at the ministry was served largely under former chief executive Martin Matthews, who has since left and been replaced by Mersi.​

"She had the chief executive's ear," a source said.

She joined the ministry's leadership team after April 2013 and was credited with establishing "organisational leadership".

Matthews said she had been "instrumental in the ministry's change achievements".

"Coming from a private sector background, Jo has brought a different level of creativity, innovation and drive to how we think about change. She helped to create a set of conditions and an environment to be more professional and innovative," he said.

As a senior manager, she was one of five people reporting directly to the chief executive, and was authorised to spend money without sign-off.

A source who worked with Harrison at the ministry said: "She came across as caring and giving but ... she would really be out to divide and conquer."

PREVIOUS WORK

Harrison previously went by the name Joanne Sharp, and worked for Tower Insurance. The Good Returns financial news website said Sharp was appointed "head of people and change" in October 2005.

As Joanne Harrison, she later worked at Far North District Council, where she again had a senior leadership position.

A council source said concerns about her history were raised after she had been appointed there.

A former colleague said she came across as plausible, and was never ostentatious. "She wasn't a person that stood out ... she was very personable and quite good at her job, actually."

Labour transport spokeswoman Sue Moroney said the scandal raised more questions about how the ministry monitored contracts.

"The minister [Simon Bridges] was surely briefed on the matter before it was referred to the Serious Fraud Office," Moroney said. "Why didn't he come clean with the public?"

Bridges' office is aware of the case, but referred queries to the ministry.