A spokeswoman said the health board would not release details of "unauthorised expenses involving potential financial breaches of Murray's obligations", due to his resignation.
"Because Dr Murray resigned, the investigation into his management of expenses was never completed," she said.
"There were therefore no findings and the DHB is legally unable to speculate on what the findings might have been had the investigation been completed."
That response was to questions put to Simcock over whether Murray spent taxpayer money on international and domestic flights, accommodation, taxis and meals for two women in non-work situations.
Further questions emerged about spending by Murray when the Herald this week revealed the investigation, conducted by an Auckland lawyer, was understood to have found evidence of travel and accommodation expenses for at least one woman Murray was not married to.
And that on one occasion Murray was unaccounted for, for several days, when he was meant to be working.
Murray, who resigned from the $560,000 a year post on October 5, was a no-show at a March 2015 United States conference and site visits he was invited to as part of a group of 35 New Zealand health-care workers.
He said he was conducting other business at the time, including meeting with IT firm HealthTap to advance opportunities for the health board's virtual health strategy, which resulted in the controversial SmartHealth app.
Expenses relating to a second woman, who worked briefly for the health board in 2014, were also understood to be a focus.
Both women were believed to be Canadian.
Murray has not returned the Herald calls and it was unclear if he remained in New Zealand.
Former Labour MP Sue Moroney, who raised concerns with Simcock about Murray before he was hired in July 2014, said she believed the DHB was on shaky ground.
"I think it's wrong of the DHB to try and hide the information that they clearly had in front of them in order to pursue the resignation of Nigel Murray."
Moroney said close scrutiny was required to monitor the spending of public money and there needed to be transparency about how it was spent.
She noted the handling of a major fraud investigation at the Ministry of Transport by its then-head Martin Matthews.
The case involved the theft of $723,000 from the Ministry by senior manager Joanne Harrison who then forced staff who blew the whistle on her out of their jobs early.
Matthews, who was promoted to Auditor General, resigned in August after his handling of the investigation was criticised but that report was never made public.
"The reason why that got so fractious is because of the lack of transparency around those processes," Moroney said.
"So my advice to the DHB is that unless they want to suffer the type of public backlash that forced the Auditor General's resignation then they should come clean and be as transparent as possible."
An investigation by Audit New Zealand into the processes and management of Murray's expenses is expected by the end of this month.