Police believe Dezi Freeman is dead at Mount Buffalo National Park.

Police say there is “no proof” Dezi Freeman is alive more than five months after he is alleged to have fatally shot two police officers in Victoria’s north-east.

More than 100 officers and volunteers launched a new search for the 56-year-old in a specific area of the Mount Buffalo National Park on Monday morning as they pursued the theory that Mr Freeman is dead.

Victoria Police Detective Inspector Adam Tilley said there was no certainty that Mr Freeman was dead in the mountainous region, but deemed it a “strong possibility”.

“There has not been any proof of life since the 26^th of August last year,” he said.

“We are comfortable that we don’t believe he is here alive.

“We do believe, strongly, that he is in this area deceased.”

The search for Dezi Freeman will be conducted over five days. (ABC News)

However, Detective Inspector Tilley said authorities were not ruling out two other key theories.

“The same three possibilities remain open to us — Freeman is either dead, being harboured, or has gotten out from the area and surviving alone,” he said.

“At this time there is no intelligence to move us away from these possibilities or to make any one the more likely scenario, so we have to keep an open mind.”

Two NSW Police cadaver dogs will be used in the search this week.

Detective Inspector Tilley said caves, mines and rivers in the area had been carefully searched and there was no evidence to suggest Mr Freeman was alive.

“This will not finish,” he said.

“This will continue. We hope to have answers this week, but if we don’t this is the number-one priority of Victoria Police.”

Dezi Freeman has not been seen since fleeing on foot into bushland behind his Porepunkah property last August. (Supplied)

Detective Leading Senior Constable Neal Thompson and Senior Constable Vadim de Waart-Hottart were shot dead, and a third officer was injured at Dezi Freeman’s rural property on Rayner Track on August 26 while executing a warrant related to alleged historical sexual offences.

Police allege Mr Freeman ran off into dense bushland behind the property shortly after the shooting.

Despite extensive searches in the days and weeks that followed, there has been no sign of the self-proclaimed sovereign citizen.

Porepunkah manhunt timeline

Authorities are searching for alleged police shooter Dezi Freeman in the north-east Victorian town of Porepunkah.

Today’s search is based on information from a witness who heard a gunshot in the area at 12:29pm, two hours after the officers were shot.

Police said they corroborated that information and have since conducted firearms testing three times near Rayner Track.

In December last year, police spent five days looking through thick bush and clearing caves in the area.

Investigators have waited until February to continue the search due to concerns about heat and bushfires.

The search is taking place in a remote part of the Mount Buffalo National Park in Victoria’s north-east. (ABC News)

In October, Victoria Police established Taskforce Summit, based in the Great Alpine area, to coordinate efforts to locate Mr Freeman.

The taskforce is led by detectives from Crime Command and includes specialist resources from the Fugitive Squad, Armed Crime Squad, VIPER Taskforce, Special Operations Group, Search and Rescue Squad and local Remotely Piloted Aircraft Systems members.

Police previously searched an area adjacent to the new search zone. (Supplied: Victoria Police)

Former homicide detective Charlie Bezzina said he believed the operation would be focused on locating Mr Freeman’s body.

“I’d be very surprised if he has been able to survive in the bush for this length of time, regardless of his expertise,” he said.

Charlie Bezzina believes police are acting on new intelligence. (ABC News: Nicole Asher)

He said police were likely to be searching for any traces that could indicate Mr Freeman’s movements following the shooting, including clothing or camping equipment.

“But it is a process of elimination to ensure that his remains aren’t there.

“It just shows the resolve of Victoria Police of not letting it go.”

Police dogs were part of the search party. (ABC News)

A $1 million reward remains on offer for information leading to the arrest of Mr Freeman, the largest arrest reward in Victoria’s history.