Henri van Breda has been found guilty on all counts in the Western Cape High Court on Monday.

Van Breda, 23, pleaded not guilty to axing his parents and brother to death, seriously injuring his sister Marli, and defeating the ends of justice. Judge Siraj Desai found him guilty on all counts.

He alleged that an intruder, wearing a balaclava, gloves and dark clothing, was behind the attack, and that he had heard other voices, of people speaking Afrikaans, in the family's Stellenbosch home in January 2015.

Van Breda claimed that, after a fight with the axe-wielding intruder who was also armed with a knife, the man had escaped.

His defence team, led by Advocate Pieter Botha, at the end of the trial insisted the prosecution failed to prove its case beyond a reasonable doubt that the Van Bredas' middle child axed his family to death, pointing out that it had no eyewitness accounts or direct evidence and its case was circumstantial.

But prosecutor Susan Galloway said there was no motive for someone - such as a hitman - to commit this crime.

State experts also found it likely his injuries were self-inflicted.