The heir to a multi-million pound fortune has claimed he single-handedly fought off a "laughing" balaclava-clad axe murderer who butchered his entire family in their beds.
Henri van Breda is accused of murdering father Martin, mother Teresa, brother Rudi and attempting to kill sister Marli in Cape Town in 2015.
If acquitted, he stands to inherit part of his family's £12million (NZ$21.8 million) fortune.
In court on Monday the 21-year-old pleaded not guilty, claiming he watched helpless through a crack in a bathroom door as a silhouetted man wielding an axe murdered his loved ones, the Daily Mail reports.
Van Breda claimed the man set upon his older brother in the early hours of the morning as he lay sleeping in his bed.
Van Breda said his shouts for help woke his 54-year-old father who turned on the light and "lunged at the attacker" to defend his son.
But he was also cut down by the killer - "who was laughing" throughout the ordeal, Van Breda's statement claimed.
Despite being aware that a "frozen" Van Breda was watching, the masked intruder then targeted the sleeping figures of mother-of-three Theresa, 55, and schoolgirl Marli, according to a statement read by defense lawyer Pieter Botha.
It was only after he had left four members of the wealthy family dead or dying, that the killer confronted the witness, whose statement described a life-and-death struggle during which he was slashed and stabbed with a knife.
As his brother laying writhing and "gurgling" on the nearby bed, Van Breda said he managed to wrestle the axe out of the killer's hands and bludgeon him with it.
When the killer came at him with a knife, he fought back as the blade was plunged into his side in the violent struggle, he claims.
As his attacker fled down the stairs, Van Breda said he gave chase, throwing the axe again at him, before falling and injuring himself.
According to reports, Van Breda's injuries were described by medical examiners as "superficial" and "self inflicted".
An "angry exchange" of voices convinced him there was more than one intruder in the house, the court heard.
Van Breda said he was delayed from calling for help for four hours after the murders because he did not know the number to dial.
He said he called his girlfriend to get the number, but she failed to pick up.
After having a cigarette to "calm" himself, he returned to the bloodbath upstairs before blacking out.
"I could hear Rudi and saw Marli moving about next to my mum who was not moving," his statement read. "I then lost consciousness."
He only woke some hours later when it was light, he claimed, and successfully phoned for help.
The first officer to arrive on the scene told the court how Van Breda "smelled strongly of alcohol" when he came to the door and appeared "nervous, not crying, but emotional".
Sergeant Adrian Kleynhans testified that a blood-smeared Van Breda said nothing about the attack on his family, and the house "didn't fit with my experience of a crime scene".
"There was a laptop on the table, plugged into the wall, there was a handbag on the table. The TV was still there," the officer said.
Wearing a grey suit and dark blue shirt, Van Breda looked unemotional, sitting behind his lawyer as his account was read to the court.
Private schoolgirl Marli, now 18, is listed as a state's witness against her brother - but prosecutors are agonising over whether to call her to give evidence or not.
Marli, the sole survivor and witness, reportedly remembers nothing about the night her throat was slashed and she was left in a coma.
The siblings have had only supervised contact since the grisly triple murder.
The murder weapons, a large kitchen knife and an axe weighing 10lbs, were carried into court by a police officer.
Martin Van Breda amassed a fortune from property and other investments while living in Perth, Australia, for seven years.
Shortly before the murders, he moved back to South Africa with his family to cash in on a lucrative business deal.
Mr Botha, who is representing Van Breda, was on the team that secured an acquittal for Shrien Dewani, a British millionaire who was accused of ordering the assassination of his new bride during their 2010 honeymoon to Cape Town.
Tomorrow, the court will reconvene at the one-time family home where the massacre took place.
It was recently and quietly sold off for £400,000 (NZ$730,000), little more than half of the going rate for such a coveted address.
A property acquire by the family on Australia's Sunshine Coast was also recently put up for sale for £1.9million (NZ$3.4 million).
Whether Van Breda will inherit his parents wealth remains to be seen - as under South African law, no one convicted of killing can profit financially from their crimes.
Van Breda denies three charges of murder, one of attempted murder and one of perverting the course of justice.