Police will conduct firearms testing within the Mount Buffalo National Park. (ABC News: Annie Brown)

Victoria Police says it is conducting firearms testing as part of a renewed search for alleged gunman Dezi Freeman in Victoria’s north-east Alpine region.

The new five-day search is underway in a concentrated area of the Mount Buffalo National Park adjacent to a region that was searched in December.

Yesterday, Detective Inspector Adam Tilley said police “believe strongly” that if Mr Freeman is still in the park, he will be dead; however, officers are open to other possibilities.

Detective Inspector Tilley said police were acting on information about a gunshot that was heard the day of Mr Freeman’s disappearance.

Police say the testing being conducted this afternoon is within the search area and similar to testing that was done in November.

They warned gunshots heard in the area would likely be connected with the tests.

A landscape showing trees with a mountain range in the background.

The search is being conducted in the Mount Buffalo National Park. (ABC News: Annie Brown)

More than 100 police from the Search and Rescue Squad, PORT, Taskforce VIPER, Critical Incident Response Team, Dog Squad and Drone Unit are helping with the search.

Police said cadaver dogs on loan from New South Wales Police would also be assisting.

Police and other specialist units standing around preparing for the day ahead.

Victoria Police prepare to continue the search for Dezi Freeman. (Supplied: Victoria Police)

On August 26, Detective Leading Senior Constable Neal Thompson and Senior Constable Vadim de Waart-Hottart were shot dead while trying to serve a warrant at Mr Freeman’s Porepunkah home.

A third officer suffered lower-body injuries in the incident.

Mr Freeman disappeared into dense bushland following the shooting, sparking a widespread police hunt, and he has not been seen since.

Dezi Freeman pictured outside a court in Wangaratta.

Dezi Freeman has not been seen since he disappeared into dense bushland. (Supplied)

Keeping an open mind

Detective Inspector Tilley said police were keeping an open mind and exploring three possibilities of what happened to Mr Freeman: whether he had died in bushland, whether he had fled the area and was being assisted by other individuals, or whether he had left the area and was on the run unassisted.

People partaking in a police search in a national park stand around a police car, they have warm clothing and backpacks.

The search for Dezi Freeman is expected to continue over five days. (ABC News)

Detective Inspector Tilley said police were hopeful the new search would turn up a trace of Mr Freeman.

“We’re hopeful that we do find something this week,” he said.

“This will not finish. This is the number one priority of Victoria Police.

“We’ve lost two colleagues and have a third member that’s seriously injured. We will not stop.”

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A bald man, wearing a navy suit and a striped tie, speaks in front of the bush

Police search for evidence of Dezi Freeman in the Mount Buffalo National Park.

Following the conclusion of the initial widespread search operation, Victoria Police created Taskforce Summit to continue the ongoing search for Mr Freeman.

Police said that more than 2,000 pieces of intelligence had been explored and a $1 million reward was still on offer for information leading to Mr Freeman’s arrest.