A search has been conducted in Adelaide's north for a man missing for a month amid fears he met with foul play.
Geoffrey McLean was last seen about 4am on August 19 when he left his home at suburban Andrews Farm to meet with some unknown people.
The 55-year-old was reported missing by his partner 10 days later.
Detective Inspector Brett Featherby from the Major Crime Investigation Branch said police had not been able to locate any evidence to suggest Mr McLean was still alive.
"Geoffrey has not accessed his bank accounts and we cannot exclude the possibility that he has been the victim of foul play," Det Insp Featherby said.
Mr McLean was known to use drugs, but police did not know if his drug use was linked to his disappearance.
He had also been known to leave his home for periods of time.
"Normally, if he has been away, he'd have contact with his family," Det Insp Featherby said.
"He hasn't had that on this occasion."
Divers, mounted police and detectives on Monday searched public green spaces and waterways around Mr McLean's home.