Rudi van Breda's attacker must have stood in a pool of his blood when his bloodied head was pushed three times against his bedroom wall after being hacked with an axe.
But why, then, was there no blood found under triple murder accused Henri van Breda's socks?
This was the question posed to blood spatter analyst Captain Marius Joubert during cross-examination by Advocate Pieter Botha when the trial resumed in the Western Cape High Court on Monday.
Botha argued that it was impossible for his client to have stood in his brother's blood and not have bloodied the underneath of his socks, pointing out that blood had only been found on the front, side and rear of his socks, not under them.
Joubert countered that there were "many possibilities", one of them being that Rudi may have been dragged by his feet to his final position, explaining the smear patterns in the blood found next to him.
"Where are the drag marks?" Botha hit back.
Blood flow patterns
Joubert admitted that he couldn't account for this in two-thirds of the stain, but had found signs of this in the final part.
When asked if any bloody hand marks had been found on the eldest of the Van Breda children, Joubert confirmed there had been none.
Smear marks had, however, been noted, meaning an object with blood had made contact with Rudi's skin, he said.
Van Breda has pleaded not guilty to charges of axing his parents Martin, 54, and Teresa, 55, and Rudi, 22, to death, attempting to murder his younger sister Marli, and defeating the ends of justice.
He alleges an intruder attacked the family in their home in the luxury De Zalze Estate, Stellenbosch, in the early hours of January 27, 2015. He claims the axe-wielding intruder ran away after the two of them struggled.
But Joubert said blood flow patterns from Henri's chest and forearm wounds didn't tie in with his claim of running after the intruder, falling down the stairs, and fainting.
'Lot of anger'
This would result in a change in position of the upper torso, he explained, with a severe fall, and fainting on stairs changing position of upper torso.
Henri's blood flow patterns, however, showed minimal movement.
He reiterated that it looked like there was a lot of anger directed towards Rudi by the attacker.
When Botha asked what, in his blood analysis, had led him to this conclusion, Joubert said that it was his opinion, and one determined from his 24 years attending to crime scenes.
Joubert was the State's final witness.
State prosecutor Susan Galloway told Judge Siraj Desai that Marli had indicated she would not like to be made available to the defence as a witness.
The trial resumes on Thursday, when Desai will hear arguments on whether the defence can change the order of Henri testifying, after his experts have been called.