Christos was last seen on Big Muster Drive, Dinner Plain, northeast of Melbourne, at around 2:45pm on Friday.
He is known to go for a walk to see emus that were said to be nearby, but he hasn’t been seen since.
“At about 6 p.m. that night, he still hadn’t returned, so his wife contacted us and she was concerned that something had happened,” said Detective Inspector Paul Hargreaves.
“He doesn’t know the area very well, but since he said he was just hiking a local trail, the Mountain Track it’s called, we believe he went there.
“What we understand is that Christos is quite fit for his age, he walks his dog for about 45 minutes every day, he is a mobile person in good health.
“We think he was in an accident or something happened to him, maybe he got disoriented, we don’t know.”
Emergency services have been looking for Christos for the past two days.
Hargreaves said a witness told SES Friday night that they saw a man who fit his “description.”
“They saw an elderly gentleman who matched the description or matched Christos’ description and we would like to hear from that person,” he said.
“They gave some brief details to an SES seeker who was away at the time. We believe that witness is most likely staying at Dinner Plain and we are currently working on the door.”
Christos was last seen wearing a long-sleeved top, long-sleeved sweater, pants and crocodiles.
“What we know at the time was that he was wearing jeans and white shoes and a dark or black colored sweater. He is bald and weighs about 65 pounds,” Hargreaves said.
Officers are concerned about Christos as temperatures are currently low and extremely windy.
“We know we have a limited time and the conditions up there can be quite dangerous,” Hargreaves said.
Anyone with information on Christos’ whereabouts is urged to contact Crime Stoppers at 1800 333 000.