A missing drone could hold the key to unraveling the mysterious disappearance of an elderly pair in Victoria's high country.

Carol Clay, 73, and her companion Russell Hill, 74, have not been since in over a month after setting up camp at Wonnangatta Valley, about a six hour drive from Melbourne.

The drone is believed to have belonged to Mr Hill.

Russell Hill, 74, and his companion Carol Clay, 73, have not been since in over a month. (A Current Affair)

His wife of 50 years, Robyn, previously told the Herald Sun she had no idea her husband was out camping with another woman.

A fire that burnt the campsite and singed Mr Hill's car – which was still drivable – has been a key focus for investigators, who have not been able to determine the cause of the blaze.

The car underwent a forensic analysis before being returned to Mr Hill's Drouin home.

Their camp was found burned out. (A Current Affair)

One of Carol Clay's close friends, Dorothy Coombe, told A Current Affair the grandmother "loved and adored" her family and wanted to see her grand-kids grow up.

"She was a tremendous friend," Ms Coombe said.

"She was one of those people who would cook you dinner and drop it around."

Mr Hills car was also burned, but not too badly. (A Current Affair)

Ms Coombe said she was surprised to learn Carol, the former Victorian President of the Country Women's Association, had regularly gone camping with Russell.

"She was a glamour Queen really.

"She always looks gorgeous and well-dressed.

"For many people, they couldn't imagine her out in the bush, let alone anything befalling her."

With little other evidence found at the scene – police have remained stumped as to whether the pair simply got lost, met with foul play or even ran off to start a new life together.

They left on March 19, with Mr Hill contacting his wife over high-frequency radio a day later. He has not been seen since.

The pair went missing after setting up camp at Wonnangatta Valley, about a six hour drive from Melbourne. (A Current Affair)

Last week, specialist officers and rescue teams returned to the site to comb through denser terrain.

Mr Hill is an experienced bushman who worked as a logger near the place he disappeared.

Local cattleman Bruce McCormack, who has assisted in many searches over the years, said the valley they were camping in was up to 1000 acres of "clear country".

"It's sort of a great open area in the middle of the Alpine National Park."

He said around one kilometre away from the campsite, the area turned into dense bushland where you would "never find them".

Parties are currently searching for the pair. (A Current Affair)

Statements from spokespeople from both the Hill and Clay families below

Hill family statement:

We are deeply saddened that Russell and Carol have been missing for one month now. Russell is our brother, husband, dad and pa and Carol has been a friend of the family for a long time. The police, SES and volunteers have searched extensively, and we thank them wholeheartedly. It is devastating for our family that we don't know what has happened to them both. We are pleading for anyone who has any information to please come forward.

Clay family statement:

Carol Clay and Russell Hill have been missing in the Wonnongatta Valley area in Victoria since 20 March, 2020.

Carol's family is very shocked and worried by their disappearance and ask for information from the community.

We appeal to anyone who may have been in the area at the same time who may have seen Carol and Russell, their campsite or vehicle. Anyone who has any knowledge at all of their whereabouts could they please contact the police.

Their disappearance is very out of character as they were well prepared and travelling in country which was well known to Russell Hill.

This is a very difficult time for our family. We are living with uncertainty, loss and the continual stress of not knowing where they are and what has happened.

At this time we ask that our privacy be fully respected while we deal as a family with the ongoing process of supporting each other, dealing with the issues this raises and helping the police.

We would also very much like to take this opportunity to extend our thanks and gratitude to the many people who have taken part in the search in difficult terrain and those who are continuing to work hard to solve what is at this stage an absolute mystery.