Triple murder accused Henri van Breda's legal team has dealt its first blow to the State's case by attacking its DNA evidence.
22-year-old Henri van Breda is accused of the murder of his parents and older brother and the attempted murder of his younger sister in their Stellenbosch home in January 2015.
The defence has called DNA expert Dr Antonel Olckers as its first witness.
Olckers is testifying on the validity of the police's forensic analyst Sharlene Otto's report on the DNA evidence she presented.
Otto tested 216 DNA samples.
Olckers has argued some the DNA evidence presented by the State is invalid.
Olckers has told the court the defence only received the data of 151 samples. She says of these, 40 were below the required input amount for DNA testing.
Olckers has told the court during her analysis of Otto's report, she discovered the Forensic Science Laboratory didn't always follow standard operating procedures (SOPs).
Olckers has stressed the importance of SOPs to be followed in forensic science, as this affects the validity of results.
She says if any non-conformance or non-compliance is found during the process, it must be registered and investigated. But this was not the case, she says, as nowhere in the hundreds of pages she looked through was there any mention of this.
Olckers says labs should have policy and procedures if any of the work does not conform to agreed requirements and corrective action should be taken immediately.
Van Breda's lawyer Matthys Combrink has asked her opinion on Otto's testimony.
Olckers says regulations make it very clear why such procedures exist, adding the lab went against its own guidelines by using these samples in its report.
The forensics specialist has also argued, just because Otto testified the results were optimal, it does not prove the analysis was correct.
Olckers says if standard operating procedures are not followed, the results technically can't be deemed valid.