The 89-year-old went missing in 2009 after deciding to walk 4km back to his house after the car he was travelling in with his wife got caught in heavy rain.
He planned to get another vehicle and pick her up, but was never seen again.
Every August we recognise National Missing Persons Week. Next week, we'll feature 8 missing persons cases, in the hope that it encourages the community to come forward with information. No detail is too small to help us find them.— National Missing Persons Coordination Centre (@AFPNMPCC) #NMPW2024 #AlwaysSearching pic.twitter.com/6bBPfcB4TgJuly 27, 2024
The case is among those police are highlighting through national Missing Persons Week, when authorities raise awareness about unsolved disappearances and cases involving unidentified remains.
Mr Ross was driving outside Glen Innes - in the NSW Northern Tablelands region - on April 26, 2009, when his car got stuck in a wash-out.
Previous investigations revealed he made it home and picked up another car, which was recovered a few days later about 70km south of his planned destination.
He might have been experiencing issues with memory loss before his disappearance, police said.
A 2012 coronial inquest determined he likely died near Guy Fawkes National Park, the area in which his car was found, but no cause of death was declared.
NSW Police Acting Inspector Matt Harmer said on Tuesday that investigators still wanted to deliver Mr Ross's family some closure.
"Any information, no matter how insignificant, could be the missing puzzle piece to solving the disappearance of Mr Ross," he said as he urged anyone who could help to come forward.
Family DNA material is being used in another cold case as police try to identify the remains of two men who went missing in a fishing boat more than four decades ago.
The men, who were aged 37 and 27, were set to go deep-sea fishing, but their boat capsized off the coast of Newcastle in 1983.
The bodies of the Vietnamese nationals, both of whom had been living in Sydney with their families, have never been found.
DNA has been obtained from family members of the two men and the duo has been added to the national missing persons database.
Police say this will give investigators the best shot at finding the mens' remains and providing answers for their relatives.
"The role of familial DNA in this case can't be understated as it may be the key to finally putting another 40-year-old case to rest, both for the families affected but also for the detectives that have stuck with it over the years," Missing Persons Registry manager Ritchie Sim said.
About 50,000 missing persons reports are made to police every year and about 2500 people remain missing.
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