A former health boss on a $560,000-a-year salary spent more than half his final year out of the office on overseas and domestic trips, expense claims show.

Waikato District Health Board chief executive Dr Nigel Murray, who resigned last month over unauthorised expenses and overspending, spent 183 days travelling in 2016/17 - leaving him a maximum of 182 days, including weekends, to do his job in Hamilton.

The cost of his expenses for that year, including flights, accommodation, meals, taxis and parking, was $91,506 - and included hiring a car for a month in Canada two days before he left North America.

Murray spent 338 days travelling during the three years he was chief executive.

Figures released to the Weekend Herald under the Official Information Act also show the board spent $145,360 investigating Murray's expenses, while paying Murray $148,521 to be on leave.

The investigation costs included almost $55,000 for an Auckland lawyer to carry out the independent inquiry, $33,585 for external legal advice and $10,889 spent on public relations.

After Murray's resignation, the DHB released receipts for his three years' worth of expenses, showing Murray spent $218,000 since he took up the role in July 2014.

In the last financial year he spent a total of 40 days travelling internationally, including three trips to the United States and Canada that the DHB has now invoiced to Murray. It's understood they were not authorised trips.

Murray was on one of those trips, to Canada, which he listed as "Professional development and completion of research project" in his expenses, when the Herald revealed on December 1 last year he had not disclosed two years worth of expenses.

Annual disclosure is required by the State Services Commissioner.

An earlier trip that year, on October 18 to 24, took in Los Angeles, New York, Montreal and Moncton.

Receipts show he hired the car on October 22, two days before he left North America. The rental ended on November 20, six days before he returned to Canada for the third trip.

It's unclear what business Murray had in those destinations.

Two weeks after Murray resigned, ending the DHB investigation into his expenses, the Herald revealed the findings were understood to show expenses associated with two Canadian women.

In the last year, Murray was travelling domestically for 143 days. This included five trips where staff queried the purpose of travel such as an eight-day stay in Auckland at a cost of $1571, and a one-way airfare from Wellington to Hamilton costing $300.

Three other stays in Auckland in February, March and April this year totalling 12 days and $4507 were also queried.

In his first year, Murray's international travel amounted to 23 days.

The cost of a 13-day trip to the United States to visit American company HealthTap near San Francisco was initially disclosed as $8929 in expenses filed by the DHB in January this year.

When the expenses were re-released earlier this month, the $8929 was amended to $1488. Receipts show Murray went to Canada for seven days during the visit.

Domestically, Murray's time away from Waikato DHB grew substantially each year.

In the 2014/15 year he totalled 45 days away from Hamilton, including travelling to Wellington twice at a cost of $877 to be involved in the recruitment for a senior role.

The next year his domestic travel grew to 69 days and included several trips to promote SmartHealth, the DHB's virtual health app powered by HealthTap.

That same year, in 2015/16, Murray's international travel added up to 18 days including three trips to HealthTap costing taxpayers $20,488.

By comparison, Murray's predecessor Craig Climo did not travel internationally in his final 18 months.

In the six months before that Climo went to one three-day conference in Australia at a cost of $3347.

In his final year Climo travelled domestically for a total of 25 days. His expenses for the two years before he left were less than $18,000.

Asked about Murray's travel spending, board chairman Bob Simcock said; "I would expect the chief executive to spend his time in the most productive way for the DHB. Nigel Murray resigned as a result of unauthorised and unjustified expenditure on travel."

Simcock said that since questions had been raised about the nature of Murray's expenses, it was essential for the DHB to carry out a thorough and fair investigation.

The State Services Commission expects a draft report into Murray's expenses by lead investigator John Ombler in the New Year.

Questions for Simcock

1. As someone with considerable experience of holding senior public positions, why did you think Murray's expenses were at an acceptable level?

2. When the State Services Commission wrote to say Murray's expenses hadn't been disclosed again, in August last year, what action did you take?

3. Why did it take from August 2016 to January 2017 to file the expenses?

4. Was there an agreement with Murray at that time that some money would be repaid? If so, what actions did you take at that time to prevent this happening again?

5. Why did you allow Murray to live at Quest for so long? Why didn't you offer assistance in finding cheaper accommodation?

6. Given Murray's history of excessive spending, why didn't you keep a closer eye on his expense claims? Did questions from the Herald in February about Murray's then $108,000 expenses prompt you to examine them more closely or question Murray on his spending?

7. Did you assure Sue Moroney you would keep a close eye on Murray, as she states?

8. What did you do to follow up on your asking of Murray to address the disjoint between doctors and management? Was this a priority?