The sister of a missing Adelaide man is pleading with him to return home, as police comb a national park in the search for clues.
Nicholas Lees, 60, was last seen in Blackwood, south of Adelaide, at the end of August.
About 20 police officers, including tactical Star Group officers, have made their way to Belair National Park, which is near the suburb of Blackwood, in an attempt to find him.
The man's sister, Sarah Hudson, said it had been a difficult time for the family.
"We're extremely worried about Nick and just hope that someone, somewhere, has seen him and might have some information to assist police with their investigations," she said.
"Nick, if you are out there somewhere, please call the police and come home, we all love you and miss you.
"Nick is a very gentle and kind person, very vulnerable at the moment, so if you do see him, please don't be afraid to approach him."
Concerns for welfare but foul play 'unlikely'
Detective Chief Inspector Scott Fitzgerald said although police did not believe Mr Lees had met with foul play, they still had no information on his whereabouts.
"We have no specific information that Nicholas would be here, however he is a Blackwood resident and just like most residents, they'll use the local area," he said.
"Today is a more concerted effort just to try and find information or any signs Nicholas may have been here at any stage."
Mr Lees has pre-existing medical conditions, but police said they were not life-threatening.
"He will be needing medication at some stage," Inspector Fitzgerald said.
"We have had people for various reasons, who have decided not to contact family or friends for a period of time, and we're hoping that's the case here."
Belair National Park covers an area of 835 hectares, including areas of rugged, mountainous terrain.
Mr Lees is described as 175cm tall, 75kg with a slim build, grey hair and a goatee beard.
Earlier this month SA Police issued a public message that Mr Lees had not been seen since 9:00am on August 30.
He is believed to be wearing clothes similar to the ones in images released by police.
Anyone with information has been asked to contact police on 131 444.
