This after the State asked for two days to prepare to cross-examine first defence witness Dr Antonel Olckers.

The DNA expert said three exhibits showed foreign alleles – on a wooden bench, Van Breda's fingernail scrapings and a duvet – indicating possible foreign DNA.

This after the SAPS forensic science laboratory results stated no foreign DNA had been found.

Olckers testified that samples analysed by the SAPS lab from the Van Breda crime scene did not meet the criteria in terms of standard operating procedures.

The defence had received data of 151 samples, although chief forensic analyst Lieutenant Colonel Sharlene Otto, testified that 216 were processed and tested.

Operating procedures questioned

Of the 151 received, Olckers said 40 samples used were below the input amount for polymerase chain reaction (PCR), which is part of the analysis process.

For this, the sample must be between 1 nanogram and 2.5 nanograms, in terms of standard operating procedures.

The remaining 111 samples used by the lab had the correct amount of DNA for PCR, Olckers testified.

In forensic science, she explained, operating outside these procedures would invalidate the results.

She also pointed out that standard operating procedures dictate that samples from the same case shouldn't follow each other on a laboratory work list.

Olckers found 116 instances where it did, explaining that the reason for this standard operating procedure was to prevent cross-contamination of samples.

In one instance, she said, DNA samples from Van Breda and his sister Marli followed each other.

"You can't call the results valid if you contravened the SOPs (standard operating procedures)," Olckers testified, saying that the guide exists to provide an international standard to allow the generation of technically valid results.

Laboratory not certified

She also pointed out that the SAPS laboratory was not accredited according to the South African National Accreditation System (Sanas).

This, however, is not a legal requirement in SA, but Olckers said the lack of accreditation meant it was not certified to have passed a standardised independent audit by Sanas.

She further in her testimony included a list of 32 DNA samples where the expiration date of the Hemastix – used in presumptive testing for blood – was not indicated.

It cannot be used after it has expired, Olckers said.

Van Breda, 22, pleaded not guilty to axing his parents and brother to death, seriously injuring his sister Marli and defeating the ends of justice.

He alleged that an intruder wearing a balaclava, gloves and dark clothes was behind the attack, and that he had heard the voices of people unknown to him speaking Afrikaans in his family's home in the De Zalze Estate in Stellenbosch 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.

The trial continues on Tuesday.

News24