Dezi Freeman has been on the run since last Tuesday following deadly violence at his property in Porepunkah, about 300km northeast of Melbourne, with no confirmed sightings of him since.
The 56-year-old is accused of killing Detective Leading Senior Constable Neal Thompson, 59, and Senior Constable Vadim De Waart, 35, while they were serving him with a warrant.
More than 400 police are searching for him on foot and in the air in Victoria's high country, with people urged not to approach him because he might be armed.
Experienced drone search and rescue operator Michael Coates said the police helicopter would have infrared and thermal cameras that detect heat through dense bushland, but warned even the most advanced technology had its limits.
"If the person is in a cave or a rock ledge or in a mine shaft and they've got no visible presence to the sky, then they basically remain unrecognised as there is no way of seeing through the ground," the C-Astral Aerospace Australia operations officer told AAP.
"If he was just out sitting under a tree somewhere, they would have found him many, many days ago."He's obviously found shelter or he's evaded everything and he's out of the area."
Victoria Police Superintendent Brett Kahan said the force believed people know the whereabouts of Freeman.
"People have chosen, for whatever reason, not to come forward, and I'm taking this time to appeal to you to come forward in that respect," he told reporters on Monday.
Supt Kahan said he couldn't confirm whether Freeman's wife Amalia would be charged after she was arrested along with the couple's 15-year-old son at a Porepunkah home last week.
"It's two different things to be speaking with police and co-operating with police," he said in reference to Ms Freeman.
Funeral arrangements for the slain officers have been finalised.
Snr Const De Waart will be farewelled on Friday, followed by the funeral for Det Snr Const Thompson on September 8.
Mr Coates said Freeman may have previously stored food and water near his home, but his survival would be hampered by his efforts to stay hidden, with police likely planting motion-sensitive trail cameras in the area.
"Normally you'd light a fire to keep warm. He obviously can't do that because the fire would show to thermal cameras like a beacon on top of the Harbor Bridge and the smoke would give him away," he said.
"He needs three things - shelter, food and water.
"If he's got those three things, it's not going to be comfortable, but he's going to be able to survive for an extended period of time".
Multiple wanted fugitives have survived for years on the run, including New Zealand man Tom Phillips who disappeared with his three children in December 2021.
Last week, local police put out a fresh appeal for information after a masked man believed to be Philips was accused over a shop robbery in the nation's north.
Closer to home, father-and-son Gino and Mark Stocco were wanted for eight years, while double murderer Malcolm Naden survived seven years on the run by raiding homes near bushland before he was caught in 2012.Mr Coates thought it unlikely Freeman could survive under the radar for that long because of technological developments.
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