UPDATE: A police spokesman said Australian Defence Force personnel would be assisting with the search for missing Marian man Sean Russell today.
He said fears for the safety of him continue to grow as extensive searches have so far failed to locate him.
Mr Russell has been missing since Saturday after becoming separated from a group whilst bushwalking on Mt Dalrymple.
Searches to date have used resources such as SES volunteers, police, a helicopter and members of the public.
EARLIER: Sean Russell, a senior associate at Kelly Legal in Mackay, has spent his third night lost on Mt Dalrymple.
Mr Russell, 46, became separated from friends and relatives while walking with them on Saturday.
A member of the Mackay Tennis Association, he worked as a solicitor in Rockhampton before moving to the Mackay region.
Mr Russell's family has requested their privacy and has declined to talk to media at this time.
Mackay police District Inspector Peter Flanders said the group had made the four-hour trek up Mt Dalrymple when Mr Russell told them he wanted to return to his car, about 4.30pm on Saturday.
"He only had a muesli bar with him, and I'm not sure if he was carrying water at the time," Insp Flanders said.
"He was wearing shorts, a T-shirt and a light jumper when he became separated from the group...
"A group can get 20 or 30 metres ahead in a matter of seconds in an area like Mt Dalrymple. You will simply not be able to see another person when you're 10 metres away, the bush is that thick.
"We had the Townsville Helicopter Rescue (searching) last night (Sunday) and it's got capabilities to pick up heat sources. But it didn't pick up anything, so that can be a good thing or bad thing."
Insp Flanders could not say how long the search would continue.
"We work on (a timeframe) medical advice," he said.
"We add some time and then tick off every box in our head to say there's nothing else we can possibly do.
At that time it's the decision of our deputy commissioner whether the search is called off."
The RACQ-CQ Rescue helicopter undertook a low-flying search yesterday, a CQ Rescue spokeswoman said.
The first mission began at 8.40am and continued until the helicopter had to be refuelled just after 11am.
It then searched for about another three hours.
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