Two seniors who went camping in Victoria's Wonnangatta Valley almost a month ago are now presumed dead, but police are investigating a range of other possible scenarios.

Key points: 73-year-old Carol Clay and Russell Hill, 74, left for a camping trip to the Wonnangatta Valley on March 19 and haven't been heard from since the 20th

73-year-old Carol Clay and Russell Hill, 74, left for a camping trip to the Wonnangatta Valley on March 19 and haven't been heard from since the 20th Last month, police officers used drones and helicopters and experienced mountain cattlemen on horseback combed the area before rain stopped the search

Last month, police officers used drones and helicopters and experienced mountain cattlemen on horseback combed the area before rain stopped the search Police say there is a chance that the pair did not want to be found and had left the site alive and together

This week, police with specialist alpine training returned to the area, along the Dargo River, to comb difficult terrain with the hope of finding some answers.

"This time we were able to look in more rugged bushland that we weren't able to search last time," Inspector Craig Gaffee said.

"Unfortunately we weren't able to find any evidence or clues that might assist us with locating Carol and Russell."

Friends Carol Clay, 73, of Pakenham and Russell Hill, 74, of Drouin left for a camping trip to the Wonnangatta Valley, north of Licola in Victoria's high country, on March 19.

Mr Hill's wife thought her husband was camping alone.

He was an experienced bushman and former logger who knew the area well.

He last made contact with his wife, using his high frequency radio, on March 20 from Wonnangatta Station and has not been heard from since.

Other campers in the area discovered their burnt out campsite at Dry River Track six days later and Mr Hill's car was slightly scorched, but driveable.

A photo of the campsite, obtained by the ABC, showed their camping chairs, tables and tent burnt but an esky and camping shower were undamaged.

Arson chemists are yet to determine the cause of the fire at the campsite in Wonnangatta Valley. ( Supplied )

Inspector Gaffee said arson chemists were yet to determine the cause of the fire and whether a mobile phone charger was to blame.

Rain hampered original search

Last month, police officers used drones and helicopters to scour the area with the help of experienced mountain cattlemen on horseback.

But the original search for Carol Clay and Russell Hill was called off due to rain.

Carol Clay and Russell Hill are presumed dead but police will search again if new information comes to light. ( Supplied: Victoria Police )

Inspector Gaffee said there was a chance that the pair did not want to be found and had left the site alive and together.

"Until we locate them there is a range of possibilities and that's one of them," he said.

"But we will continue to investigate the circumstances and hopefully bring some conclusion to the matter for the families.

"At this stage we think they are still in the Wonnangatta Valley and likely deceased.

"But there are a range of different scenarios and investigations that we are conducting to try to locate them."

Inspector Gaffee said Mr Hill's wife was expecting him home by the end of March.

"Clearly she's distressed. Both people have got family and friends who are really, really worried, as are the police," he said.

"Everything is on the table. If we were to establish some more evidence or receive other information … we would be more than willing to go back up there and search again."