By Melissa Meehan and Farid Farid in Melbourne

Australia’s most wanted man, Dezi Freeman, is strongly believed to be dead as police begin a fresh search for his body in dense high country.

Victoria Police started a five-day dragnet for the fugitive, or his remains, at daybreak on Monday using cadaver dogs and specialist officers from around the country.

It is the latest search in the five-month manhunt for the 56-year-old after the fatal shootings of police officers Neal Thompson and Vadim de Waart-Hottart.

The pair were among a team of officers serving a warrant at Freeman’s home in the small northeast Victorian town of Porepunkah in late August.

Detective Inspector Adam Tilley said there had been no sightings of Freeman since the shooting,  and police were keeping an open mind about what had happened to him.

They are working on three scenarios, including that he is dead in the national park, has escaped the park and is being harboured by others or that he had escaped the area without any help.

“We don’t believe that he is still in the area alive,” Det Tilley told reporters at the scene on Monday.

“We are comfortable that we don’t believe he is here alive … we do believe strongly, that he is in this area deceased.”

More than 400 police deployed in the days after the killings failed to uncover any trace of Freeman, who was last seen fleeing into dense bushland in the alpine region shortly after the shootings.

Detective Senior Constable Thompson, 59, was just a week away from retiring, while Senior Constable de Waart-Hottart, 34, was on temporary assignment to the area.

On Monday, police began a fresh, five-day search of Mount Buffalo National Park including remote sites in the region about 300km northeast of Melbourne.

Investigators in December revealed they had shifted their search efforts to locating the body of the self-described “sovereign citizen”, however a five-day effort to scour the bush with cadaver dogs and drones yielded nothing.

Detectives said firearms testing previously undertaken by police had shaped their renewed search area.

Officers will focus on a region close to a previously probed area based on intelligence gleaned about a gunshot heard soon after the fatal shootings.

Officers from Taskforce Summit, formed in October, have investigated thousands of pieces of intelligence including numerous tip-offs from the public.

Det Tilley said finding Freeman was the force’s “number one priority”.

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

“What we want most is to see this through to resolution and hopefully provide answers and some level of comfort to Neal and Vadim’s families, the other police impacted and the wider community.

“We will continue to do everything we can to achieve that.”

Victoria Police have offered a $1 million reward and the possibility of indemnity for information leading to Freeman’s capture.

It is the largest reward in the state’s history for facilitating an arrest.

Despite no confirmed sighting of the trained bush survivalist since the shooting, Victoria Police Commissioner Mike Bush previously said investigators would not give up until they found him.

Bright and District Chamber of Commerce president Marcus Warner said residents were surprised to wake up to news of another search for Freeman, but eagle-eyed locals had noticed the town’s accommodation and cafes were busy on Sunday with arrivals.

“I think it will be obviously a bit of a morale boost and a psychological boost for the community that they’re back searching,” he told AAP.

Freeman’s wife Mali and a 15-year-old boy were previously arrested but released without charge.