“I did not find any unknown DNA at all from the scene of the crime.”

These words‚ uttered by Lieutenant-Colonel Sharlene Otto — a chief forensic analyst on the stand in the Henri van Breda triple axe murder trial — were at the heart of a heated exchange in the High Court in Cape Town on Monday between state prosecutor Susan Galloway‚ and counsel for the defence Piet Botha.

Otto’s DNA findings put a bigger question under the spotlight: Is it possible that someone came to 12 Goske Street at the luxury De Zalze estate in Stellenbosch‚ wiped out three members of the Van Breda family with an axe in 2015‚ and left no trace that they had been there?

Henri van Breda‚ 22‚ stands accused of killing his parents and brother‚ and attempting to murder his younger sister Marli.

It was revealed earlier in the day that DNA of his mother‚ Teresa‚ and brother‚ Rudi‚ were found under his fingernails and in blood stains on his shorts.

His legal team‚ however‚ has argued that an intruder came in and carried out the dastardly deeds.

After Otto said no trace of unknown DNA was found at the scene‚ Galloway asked: “What are the odds that a person entered‚ committed a crime and left no DNA?”

Botha objected‚ and then Galloway instead asked Otto to explain the Locard Principle.

“Every touch leaves a trace‚” explained Otto‚ “that is the first rule of forensics.”

When Galloway then asked how an intruder could be responsible for the murders but not leave DNA‚ Botha objected and accused her of speculation.

Judge Siraj Desai let Otto respond‚ and she said‚ “Only if you wore a full PPE‚ you won’t leave a trace on the crime scene.”

PPE stands for personal protective equipment‚ which is – according to the UK’s Health and Safety Executive — designed to protect against safety risks at work and includes items such as gloves ‘’eye protection‚ high-visibility clothing‚ safety footwear and safety harnesses’’.

The analysis of the crime scene had focused on 216 samples – “far more than the usual number”‚ according to Otto.

She said the defence team had asked for a paper trail which documents every aspect of their analysis – from the credentials of the analysts‚ to the extraction process‚ to the raw data‚ positive and negative controls‚ and standard operating procedures.

“We numbered the pages in the file‚ and it came to around 3‚000 pages‚” said Otto‚ adding‚ “The actual exhibits are all still available because one of the international guidelines is that either part of a swab is kept for further analysis or the DNA extraction itself is kept.”

Botha also objected that his team had not been privy before Monday’s proceedings to a new DNA test done on a swab taken from the door of the laundry room downstairs at the house.

But‚ said Otto‚ the sample had proven to contain no DNA – either because it gave a false positive that it was blood in the first place‚ or because it was possibly animal blood which was there because of the laundry room’s proximity to the kitchen where meat is prepared for meals.

The case continues.