A former Waikato DHB chief executive spent $91,000 of taxpayer money in 2017, his expense records released on Friday show.
Nigel Murray resigned in October over an investigation into his charging of expenses to the DHB, after a tip-off from senior staff.
Information about Mr Murray's expenses show he spent thousands of dollars on hotels in Auckland, which were not signed off by Waikato DHB chairman Bob Simcock.
In September, 2016, Mr Murray spent $3184.00 on accommodation for an undisclosed period of time at the Langham hotel.
In August 2016, Mr Murray also spent $1734.20 on a 15 day stay at the Langham for an undisclosed reason, which was not signed off prior by Mr Simcock.
The Waikato DHB said in its release that they were unable to provide a comprehensive answer to what expenditure was authorised and what was not but it could "be assumed that if a claim form has not been signed off, the expenses to which it relates were not authorised".
Over his three years as chief executive, Mr Murray spent $91,506.34 for the financial year ending 2017, $45,763.56 for the year ending 2016 and $80,896.55 for the year ending 2015 (including $50,000 on relocating from Canada to Hamilton when he first took the job in 2014).
Health Minister David Clark announced Friday that an investigation would be undertaken by the State Services Commissioner into Mr Murray's misspending.
"It is critical that transparency in and accountability for these processes and outcomes is maintained," Mr Clark said.
"I expect that this investigation may involve considering whether appropriate standards of integrity and conduct have been maintained by Dr Murray and the DHB."