A 20-year-old man from the South Australian Riverland has admitted that he brutally murdered a woman at Loxton.
The man has pleaded guilty in the Supreme Court on a charge of murdering 53-year-old Nina Starr.
The court heard that he used a 44 cm spanner to bash Ms Starr while she was out walking.
Her badly-beaten body was found floating in the River Murray in January last year.
The man will receive an automatic life prison sentence for murder.
Justice Margaret Nyland will consider setting a non-parole term later.
Outside the court, Ms Starr's family expressed relief at the guilty plea but said it did little to ease the grief.
