In October the Herald revealed the DHB's investigation into Murray's unexplained spending showed receipts associated with two Canadian women. The Herald can now identify Sainiuk as one of those women.
The investigation ended when Murray resigned in October and the draft report, by an Auckland employment lawyer, has never been released publicly.
Last month the State Services Commission inquiry into Murray's $218,000 worth of expenses during his three years in the top job found $120,000 was unauthorised or unjustified.
Murray has since paid back the $74,000, but the case is now before the Serious Fraud Office.
In information released to the Herald under the Official Information Act, the DHB confirmed Sainiuk "did some work" for the DHB between October 10 and 26, 2014, three months after Murray took up the $560,000 per year post.
Murray was CEO at Fraser Health Authority in British Columbia for seven years before he returned to New Zealand.
In an email to Sainiuk dated October 8, 2014, Murray thanked her for agreeing to "visit with us here in Hamilton".
"This will create a unique opportunity for us to advance our quality frameworks especially in regard to accountability of middle ranking clinical managers, which I know you have had a strong interest in over the years."
Murray went on to say that he was developing a programme of work for Sainiuk's time at the DHB and would forward her a letter of engagement.
"Once again, thank you for helping us out and I look forward to your visit."
Sainiuk reported directly to Murray and the DHB understood her brief was to share her experience and research around patient safety activities and assist staff to develop an accountability and responsibility framework.
However, Waikato DHB spokeswoman Lydia Aydon said the DHB had no record of a letter of engagement, no record of payment to Sainiuk, no written programme of work, and no report by Sainiuk detailing her work or benefits to the DHB.
"She did have meetings with staff in the nursing directorate and patient and quality safety but we have no record of a written programme of work. I understand it was a verbal agreement with the CE at the time."
The $6540 was not part of the $74,000 identified by the DHB as personal spending by Murray and the DHB did not request it be repaid.
Aydon said Murray had delegated authority to appoint staff or contractors and it was not unusual for the DHB to pay for experts to visit Waikato Hospital.
Sainiuk, now the eastern access emergency manager at Mount Saint Joseph Hospital in Vancouver, has not responded to phone and email messages from the Herald regarding her visit to Waikato Hospital and arrangement with Murray.
Questions to Murray's lawyer also went unanswered.