A SCOTTISH teenager raped and then stabbed a 16-year-old pregnant girl more than 30 times and knifed her parents around 80 times after breaking into their home in Australia.

Jason Downie admitted the triple murder of Andrew and Rose Rowe and their teenage daughter Chantelle, when he appeared at the Supreme Court in Adelaide.

Downie, 19, who is originally from Onthank, Kilmarnock, had become "sexually obsessed" with Chantelle and jealous of his friend who was dating her.

In his defence, Downie's lawyer claimed the car mechanic, who moved to Australia six years ago, had seemingly unleashed "superhuman forces" on the night of the murders, given the ferocity of the knife attacks.

Downie broke into the Rowe home in Kapunda, near Adelaide, on November 8, 2010, where he stabbed Mr Rowe at least 29 times and Mrs Rowe more than 50 times, with her wounds suggesting that Downie continued his savage attack as she tried to crawl away on her hands and knees.

Their daughter Chantelle suffered more than 33 separate stab wounds, and forensic evidence showed the teenager was also raped by Downie.

Director of Public Prosecutions, Stephen Pallaras, said: "It is no exaggeration to say that the hallway and floors throughout the house were covered in blood.

"It appears from the position of the bodies of Andrew and Rose Rowe and the positioning of their blood that, even after he had stabbed them and attempted to clean up their blood, he went back to them and stabbed them again."

Mr Pallaras said that after the murders, Downie "paid tribute" to the Rowes and consoled Chantelle's boyfriend, until the identification of his DNA led to his arrest.

Downie had re-dressed Chantelle in clean clothes after he had killed her and had stabbed her parents so hard that bits of the weapon were left in their heads.

Defence counsel Greg Mead, QC, said Downie's infatuation with the teenager had turned to resentment and anger and ultimately homicidal rage.

Mr Mead said many would think his "weedy" client, who weighs just over eight stone, would not be capable of such a crime.

He said: "He unleashed an attack which will not seem possible from someone of his stature. It was as if superhuman forces were unleashed within him. Obviously he went completely beserk that night. He seems to have lost all control.

"[He was an] immature young man who could not have been aware he was capable of such violence."

The defence lawyer said Downie originally told police "stupid, childish lies", but that had "simply emphasised his lack of maturity". He eventually took police to where he had dumped the clothing and shoes he wore during the attack. He also took police to where he said the murder weapons had been dumped, but none were found.

Mr Mead said Downie could not remember much of the attack, but was beginning to understand the enormity of his crime and deserved credit for his admission of guilt. He said: "He has written a letter of apology to the family of the victims but admits no words will restore the Rowes to their family."

Mr Mead said Downie's own family had been shocked by the nature of the crimes. "His family must have found it unbelievable this skinny young man, who has never answered back to his mother or been in a fight, had committed this crime," he said.

Mr Mead said his client experienced a mental "numbing" after the murders.

Prosecutors stressed that at no time was Chantelle in a relationship with Downie.

Justice Sulan, who will sentence Downie next month, is in the process of hearing 26 victim impact statements written by the family's surviving son, Christopher, and their friends and family.

Downie, who earlier confessed to the killings, showed little reaction during many of those statements.