SAPOL says it is worried missing mother Tanja Ebert has met with foul play.
Ms Ebert, 23, was last seen on 8 August when she reportedly got out of the family car at Roseworthy and walked off leaving behind her husband, two boys aged 1 and 3.
“We have searched this area… and have found no trace of this young woman,” Detective Superintendent Des Bray said.
“We have grave fears that she has been murdered, although we’re holding out some slim hope that we’re wrong.
“I’m asking that anyone who has had recent contact with her to come forward and speak with investigators by calling Crime Stoppers on 1800 333 000.”
Ms Ebert, a German citizen, met and married her husband shortly after arriving in Australia in 2012.
“We are aware there had been some issues in the marriage, however at this time we are keeping an open mind with regard to suspects,” Detective Bray said.
“As with matters of this type, we are making inquiries to rule out the involvement of those who saw her last.”
“Unfortunately there have been no signs that she is alive, and we fear she has been murdered.”