The family of missing South Australian mother Trisha Graf say they now believe she has been murdered as a fresh outback search fails to uncover any new clues.

Graf, a mother of six, vanished a month ago in Andamooka on December 12 with detectives now declaring her disappearance a major crime.

The officers returned to the remote town this week in a renewed push for answers.

Officers gathered in the centre of Andamooka on Wednesday, determined to piece together what happened before the 41‑year‑old disappeared.

For her family, hope has given way to fear.

“I was in denial but now I know something is wrong — I just want her home,” her mother, Anne Graf, told 7NEWS.

Her daughter, Montanah Shaw‑Graf, says the family is convinced something sinister has occurred.

“Something has happened to her and it’s just not normal for this to happen,” she said.

“She would never, ever leave her kids.”

Graf left Roxby Downs Hotel at 12.19am on December 12 in her car, accompanied by a friend.

Her car was damaged in a collision with a kangaroo before she and her friend continued their journey and visited a home in Andamooka.

Graf then left that house just before 2am to travel the short distance to her home and was last seen driving on Dunstan Dr Andamooka.

Her abandoned and damaged car was discovered by her partner at Blue Dam, about 7km from town — a place her family insists she had no reason to visit.

“He said she never even knew where Blue Dam was,” Anne said. “I asked, ‘Well, how did the car end up there if she didn’t know where it was?’ None of it makes sense.”

“I don’t believe Trish drove that car there. Someone drove that car there.”

Anne now believes her daughter has been murdered.

“I think something really bad has happened to her,” she said.

“It gives me nightmares, but I do believe something has happened to Trish and she can’t speak for herself.”

Police have interviewed the last people to see Graf before she vanished, including her partner, who investigators say is cooperating.

7NEWS contacted Graf’s partner for comment but he said he cannot speak publicly at this time.

As detectives continue to sift through evidence and timelines, the tight‑knit outback community is hoping this mystery — one now feared to be a killing — will finally be solved.