A man accused of killing three people at a property in Adelaide's north in 2016 has pleaded guilty to the murders of two children.
Steven Graham Peet, 31, previously pleaded guilty to murdering his partner Adeline Wilson-Rigney, but at the time denied murdering her daughter and son.
He argued he was in a state of mental dissociation after killing Ms Wilson-Rigney and could not have formed an intent to murder the two children.
The court heard the author of a psychological report which initially supported Peet's claims of dissociation now had a "revised opinion".
He was expected to stand trial on the remaining two charges today but instead pleaded guilty to murdering six-year-old Amber Rose Rigney and five-year-old Korey Lee Mitchell.
The court previously heard all three victims had been strangled with cable ties.
Ms Wilson-Rigney's body was found under a mattress in the laundry.
Prosecutor Ryan Williams previously said the two children were tied up, suffocated and strangled, while their mother was repeatedly hit in the head, possibly with a crowbar.
There was evidence that Korey had tried to remove the tape around his mouth and kick his way out of a wardrobe he had been locked inside.
Forensic evidence, including DNA, allegedly linked Peet to the children's deaths.
Peet faces a mandatory sentence of life imprisonment.
The Supreme Court will hear submissions to determine the length of his non-parole period next month.
