Cape Town – Even though Henri van Breda’s defence team had access to DNA samples taken at the family’s luxury house, they opted not to retest them, the Western Cape High Court heard on Thursday.Dr Antonel Olckers, the defence’s first witness who has been questioned for six days, said retesting the samples was not part of her mandate.The DNA forensic expert was being cross-examined by the prosecution.She told the court that she considered the SAPS forensic science laboratory results “scientifically invalid” because the analysts had not followed its standard operating procedures (SOPs) by the book.This includes that samples from the same case may not follow on a work list and the size of 39 of the analysed DNA specimens being under 1 ng.'Invalid results'She said the outcomes could possibly be wrong or invalid and shouldn’t be relied upon.Galloway asked why she didn’t do her own analysis by retesting the samples.She responded that Van Breda’s counsel did not ask her to do so.Olckers, who was mandated by the defence to assess the scientific validity of the SAPS reports, sat in court when State witness, chief forensic analyst Lieutenant Colonel Sharlene Otto, testified. She passed notes to the defence team and whispered to them during cross-examination.Galloway said the number of forensic samples – 216 had been analysed – resulted in logistic issues, such as the same case samples following on the work list.A matter of qualityOlckers responded that cases with a lot of samples could not be handled differently and must still comply with SOPs because one “can’t sacrifice quality”.Galloway pointed out that Otto’s objectivity and quality controls were of such a nature that she didn’t confirm one of the samples as that of Martin van Breda as it was two alleles short.The prosecutor also pointed out Olckers had never worked in a forensic laboratory.READ: Van Breda expert witness never worked in forensic lab - StateOlckers, however, said biological processes are generic.Two previous cases in which Olckers was criticised were also raised by the State.In one the judge said she had requested “voluminous” files of documents which resulted in 11 lab personnel being cross examined in 10 court days, and which resulted in her only concluding that the “culture of the lab could not be relied upon”.Her practical experience and statistical knowledge was also criticised.Judge Siraj Desai asked if two judges were unhappy with her, but the defence objected, saying she only testified in one of the trials.Desai: so 2 judges were unhappy with you? Adv Combrink objects, says she only testified in one. #VanBreda— Tammy Petersen (@TammyPetersen87) October 19, 2017Olckers appeared flustered, eventually opting not to answer.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 clothing, was behind the attack, and that he had heard other voices, of people speaking Afrikaans, in their 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.Before completing her testimony, Desai asked Olckers if she could explain why Marli’s blood was not found on the axe, but that her touch DNA was present.She explained that while she was not a blood spatter expert, the touch DNA could have been on the axe from any time.Olckers was unable to confirm how long touch DNA could remain on an item.The trial continues on Monday when neurologist Dr Michael Du-Trevou is expected to testify.