Police “strongly believe” accused cop killer Dezi Freeman could be dead as a fresh five-day search for the fugitive begins in Mt Buffalo National Park.

More than 100 police officers, including members of the dog squad, drone squad and volunteers, have kicked off a five-day search for Freeman near where he was last known to be.

Investigators are working on three possible theories over Freeman’s whereabouts after he was last seen on August 26 last year, one being that he is no longer alive.

A new search for alleged police shooter Dezi Freeman kicks off this week. (A Current Affair)

Police are also not ruling out that a member of the public is harbouring him or that he is on the run, alone.

“We are currently exploring three scenarios: the first is that Freeman is dead, either by self-harm or misadventure,” Victoria Police Detective Inspector Adam Tilley said today.

Tilley added that police do not think Freeman is alive in the area they are searching and “strongly believe” he is deceased.

“The second [theory] is he has been able to escape the area and is being harboured by a person or people,” Tilley continued.

“And a third scenario we are exploring is that he has left the area and is on the run unassisted and he has not been located.”

A fresh search for Freeman kicked off in Mt Buffalo National Park today. (9News/Supplied)

Despite the theories, Tilley said police have not received any proof of life or intelligence that suggests Freeman is still alive.

Detectives have investigated over 2000 pieces of information so far.

Today’s search was launched following a tip-off that a single gunshot was heard around 12.20pm on the day police officers Neal Thompson and Vadim De Waart-Hottart were shot dead on Freeman’s property at Porepunkah.

Firearm testing was conducted in November in the vicinity of Barrett Lane and Rayner Track.

This testing led police to identify additional search locations in the ongoing manhunt.

Tilley said police have not received any proof of life or intelligence that suggests Freeman is still alive. (9News)
Detective Inspector Adam Tilley said police are exploring the possibility Freeman could be dead. (9News)

“This week we are here to conduct an ongoing search based on that information,” Tilley said.

This week’s search will span 1.3 square kilometres, which is around 52 football fields in size.

Police, search and rescue volunteers, members of the dog squad and drone squad will join the five-day search, expected to end on Friday.

“Weather is on their side but it will be extremely challenging,” Tilley said, noting the search may be hampered by difficult terrain and thick bush.

Mount Buffalo National Park has already been the focus of police activity in the hunt for Freeman, with a five-day search undertaken in part of the park last December.

Thompson and De Waart-Hottart were shot dead when officers were executing a search warrant on Freeman’s property as part of an investigation by the Wangaratta Sexual Offences and Child Abuse Investigation Team.

A third police officer was seriously wounded and continues to recover.

Police have maintained a presence in the region since the shooting in August last year. (Joe Armao)
The new search will focus on Mount Buffalo National Park. (Victoria Police)

Police say there is no specific intelligence to suggest Freeman, a self-proclaimed “sovereign citizen”, is being assisted by somebody in the local community, but it remains a possibility.

A $1 million reward has been posted for information leading to his arrest – a first in Victorian history.

“This incident, which resulted in the deaths of Neal and Vadim, continues to have a significant impact on both Victoria Police and the Porepunkah community more broadly,” Detective Inspector Adam Tilley said.

“It remains our number one priority to locate Freeman and the extensive and systematic searches conducted over the past five months are testament to this.”

Freeman is a self-declared sovereign citizen. (A Current Affair)

He said police remained convinced information from the community would be crucial to the case and urged anybody with any knowledge to come forward.

“This could be anything you have heard about Freeman’s actions on the day or the shooting or his current whereabouts, or anything you may have seen in the Mount Buffalo National Park area that you think is suspicious or could be connected to Freeman,” he said.

“If you do have any information, then I urge you to contact police or Crime Stoppers and as always, this can be done confidentially.”

Meanwhile, anybody who sees Freeman is urged not to approach him but to call Triple Zero immediately.