SA Police have returned to the outback town of Andamooka to search for missing local woman Trisha Graf.Ms Graf, 41, was last seen driving in the town, about 600 kilometres north of Adelaide, in the early hours of December 12 last year.The next day, her car was found abandoned near Blue Dam, about 4 kilometres east of Andamooka.Police say investigators will search for evidence on the western fringe of Andamooka "over the next few days".Police have conducted several searches over the past five months looking for the mother-of-two.Most recently, in March, they seized a car and searched locations including mine shafts and disused opal diggings.Police say Ms Graf went to the Roxby Downs Hotel with a friend on the night of December 11 and was last seen there at 12:19am.The pair then drove back to Andamooka, hitting a kangaroo on the way but continuing to the smaller town. Ms Graf left her friend's house just before 2am and was last seen driving along Dunstan Drive, in Andamooka.Ms Graf's partner and a friend found her car immobilised on a mound near Blue Dam about midday on December 12.Her disappearance was declared a major crime on January 6.Police have asked anyone with information about Ms Graf's whereabouts or her movements leading up to her disappearance to contact Crime Stoppers on 1800 333 000 or online at www.crimestopperssa.com.au.