Police believe Dezi Freeman took his own life after killing two police officers, as they launch a new search of Mount Buffalo National Park honing in on the location of a single gunshot heard in the wake of his murderous rampage.

Detectives believe Dezi Freeman is likely dead in the bush after a single gunshot was heard after he murdered two officers at Porepunkah.

Detectives say they believe Dezi Freeman is dead in the bush after a single gunshot was heard and recorded following his murderous rampage at a remote property at Porepunkah in Victoria’s northeast.

Police on Monday launched a fresh five-day search of Mount Buffalo National Park with the hopes of finding Freeman’s body after he murdered two officers five months ago.

A member of the public last year came forward to police with the belief they had heard a single gunshot about an hour after Freeman escaped into the bush on August 26.

Detective Inspector Adam Tilley said the tip-off of the gunshot was supported by further evidence gathered by detectives from Taskforce Summit, the squad dedicated to finding Freeman.

Insp. Tilley said the report of the gunshot was the “strongest piece of information” obtained by investigators so far.

He said the most likely scenario was that Freeman had shot himself as there had been no signs of life reported anywhere.

“Yes, it’s been corroborated by other parts of the investigation,” he said on Monday morning.

“We’ve obtained a statement from that person and we’ve made a number of avenues of enquiry and we’re comfortable that we believe it was a gunshot around 12.29pm.”

Various firearms tests at several locations after the report was made helped pinpoint the location of this week’s search, which spans 1.3 square kilometres.

Insp. Tilley said Summit detectives were still exploring three possibilities but they widely believed Freeman to be dead.

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

“We have done extensive searching of the caves, the mines, the huts, the rivers. We are comfortable that we don’t believe he is here alive.

“There has not been any proof of life since August 26.

“(But) we don’t have intelligence or information that supports any one theory more than the other. We are live to the three scenarios, and at this point, all three are live and active.”

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More than 100 police and volunteers scoured the rugged terrain on Monday in extremely challenging and warm conditions.

A cadaver dog, which specialises in sniffing out human remains, was brought in from New South Wales to support the major new search.

“It’s even harder than what was conducted in December … to make it clear, it’s not going on a bush walk,” Insp. Tilley added.

“It is steep, it is thick, dense bush. (There are) parts where you don’t even know where you’re stepping, you have to be extremely careful.

“Safety is an issue for everyone because of the terrain.”

The latest search is expected to last five days. Picture: Simon Dallinger

Police are focused on a single gunshot heard coming from the bush after Freeman’s rampage. Picture: Simon Dallinger

Insp. Tilley, who was on the ground searching for Freeman during the December search, said finding the killer remained the force’s “number one priority”.

He said it would give closure to the families of Detective Leading Senior Constable Neal Thompson and Senior Constable Vadim De Waart-Hottart.

“I can speak on behalf of every detective on this taskforce. We want answers, we want a resolution,” he added.

“(The families) have questions. We would like to provide them with some answers and some level of comfort.

“We’re thinking positively, we hope to have an answer this week, we’d like to find something, find him, maybe an item of clothing.”

The $1m reward for any information leading to the location of Freeman remains on offer.

The two members were part of a group of about 10 officers carrying out a search at the sovereign citizen’s bush property over historical allegations of child sexual abuse.

Freeman killed the two officers, wounded a third and tried to shoot a fourth before he ran into the bushland.

The Herald Sun later revealed he had tried to shoot the fourth officer, but his firearm failed to discharge.