"What I can say is the complaint by MHN [Midland Health Network] did not in any way signal inappropriate use of expenses at that time," he told the Herald.
Simcock's departure, announced by Minister of Health Dr David Clark on Tuesday afternoon, was welcomed by critics including board member Dave Macpherson who said it was finally the "right thing".
But acting board chairwoman Sally Webb, the former deputy chair and chairwoman of Bay of Plenty DHB, said a lot of people at Waikato DHB were saddened by the news.
"He's been a well-intended and well-respected chair, but Bob made his decision and we all respect that decision."
She had not given any thought to whether any other board members should resign, Webb said.
"I would imagine that everybody else on the board is committed to the same thing as me, focusing on what we're there for and that's the delivery of high-quality health services, not only to Waikato but the whole of the Midland Region."
The board was hugely committed to the wellbeing of Waikato DHB staff and helping them to do their work as best they can, she said.
It was up to the SFO to decide if it would pursue an investigation, Webb said.
An investigation is triggered by the SFO Act, involving formal powers, where the director has reason to suspect that an investigation into the affairs of any person may disclose serious or complex fraud.
Board member Martin Gallagher, who is also Hamilton's deputy mayor, said he now wanted to know what red flags were missed leading up to the scandal.
"There's issues of accountability and my concern is what red flags should I as an individual board member have picked up, and that's the learnings. How do we improve the red flags?"
Gallagher, who was one of the board members who hired Murray and also signed off the controversial proposal for HealthTap - the American company that provides the DHB's virtual health app - said there was no intention by any other board members to resign.
"There's three external inquiries [SSC, SFO and Audit NZ] happening and when they come back and obviously with natural justice I assume the minister would go from there.
"At that point it will be clear what learnings and conclusions can be taken from those inquiries."
Gallagher said he was sorry to see his former central government political opponent Simcock go.
"I found him really good to work with as a chair. No one disputes his passion for health in the region.
"I totally accept there's a process of inquiries to go through and they will reach their own conclusions."
A damning Audit NZ report into the management processes around Murray's expenses, which the Herald revealed on Friday, will be officially released by the DHB on Thursday morning.
