A Melbourne man has been arrested over the disappearance of campers Russell Hill and Carol Clay in Victoria's rugged high country 20 months ago.
The 55-year-old man from Caroline Springs was arrested about 5.30pm on Monday, Victoria Police said.
He will be interviewed by detectives on Tuesday morning. No charges have been laid.
Mr Hill, 74, and Ms Clay, 73, were last heard from on March 20, 2020, while camping in the Wonnangatta Valley.
He was last heard from on March 20 when he made a call via HF radio saying he was at Wonnangatta Valley in the Victorian Alps.
Ms Clay told friends she was heading away and expected to return home on March 28 or 29.
Investigators were told the couple were camping together at Wonnangatta River near the Wonnangatta camping ground.
Campers found Mr Hill's fire-damaged car at their campsite, which was completely destroyed by fire, near Dry River Creek Track on March 21.
The pair have not been seen or heard from since.
Earlier this month, police released images of a blue four-wheel-drive - believed to be a mid-to-late-1990s model Nissan Patrol - taken by a safety camera in the area at the time Mr Hill and Ms Clay went missing.
Witnesses reported a number of sightings of the vehicle, with police yet to pin down the driver or exclude the driver as a person of interest.
Police believe the pair may have had an altercation with another camper at the campsite, possibly the driver of the blue 4WD.
Australian Associated Press
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