More specialist officers arrived in Dargo on Monday afternoon as police scaled up their search for Russell Hill and Carol Clay, who have been missing for 20 months.

The search has moved to bushland north of Dargo, a remote town in the alpine region, less than 40 kilometres from where the couple were camping together when they went missing in March 2020.

It is there, in dense and dangerous bushland that is difficult to navigate, that police believe they will find the answers they seek.

Monday's search involves Missing Persons Squad detectives, Search and Rescue crews and Victoria Police's Major Crime Scene Unit.

"We have a considerable number of police specialist resources attending... it is going to be a painstaking search that could take some considerable time," Inspector Matt Gleeson told ABC Gippsland on Monday.

Investigators were told the couple were camping together at Wonnangatta River near the Wonnangatta camping ground.

Greg Lynn, 55, has been charged with two counts of murder and is now at Melbourne Assessment Prison.

While announcing Lynn's charges last week, Assistant Commissioner Bob Hill warned the police investigation was "far from over".

"We are hopeful that we will locate the remains of Mr Hill and Ms Clay ... and provide closure to their families," he told reporters.

Mr Hill and Ms Clay were last heard from in March 2020 when Mr Hill, an experienced outdoorsman, made a call via high-frequency radio saying he was at Wonnangatta Valley.

Campers found Mr Hill's car destroyed by fire at their campsite near Dry River Creek Track on March 21.

Police also want to speak to anyone who was in the Wonnangatta area about that time, including "campers, 4x4 daytrippers, hunters, fishermen or trail bike riders", regardless of whether they saw or heard anything.

Australian Associated Press