The man who killed Jody Meyers and buried her under a concrete slab should be locked up with the key thrown away, the victim's family says.
Neil Anthony Archer has pleaded guilty to murdering his 20-year-old partner in the South Australian town of Mannum in August 2015.
"Guilty, your honour," the 31-year-old admitted in Adelaide Magistrates Court on Tuesday.
Members of the murdered woman's family were in court for the hearing, including her mother who broke down in tears after the guilty plea.
Ms Meyers' brother-in-law Michael Bates said the family knew all along that Archer did it but they were relieved it was now official.
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They hope the law comes down hard on the killer when he is sentenced next year.
"Don't let him out, throw away the key," Mr Bates said outside court about what he thought would be a fair sentence.
"We don't get Jody back so why should he get a life?
"He deserves to rot in a cell as far as I'm concerned."
Ms Meyers' body was found buried under a concrete slab at Archer's parents' property in Mannum more than a month after she went missing.
The discovery came after a widespread search in which divers scoured the Murray River and mounted police combed roads in pursuit of clues.
Prosecutors have earlier said they believed Archer used a piece of grey cord to kill his partner.
The killer's mother Margaret Archer also faced court on Tuesday, accused of helping her son in the aftermath of the murder in an attempt to escape prosecution.
She pleaded not guilty to the charge of assisting an offender and she will stand trial next year.
