DNA expert grilled over validity of samples

THE defence’s DNA expert in the trial of alleged axe murderer Henri van Breda told the Western Cape High Court that there was not enough DNA in 40 samples taken from the crime scene to yield valid results.

Dr Antonel Olckers faced her third day of gruelling cross-examination in the trial of 22-year-old Van Breda, who is accused of the axe murders of his parents and brother, and the attempted murder of his sister at their home in a security estate in Stellenbosch in January 2015.

Olckers told the court that “one cannot make a valid conclusion from an invalid interpretation”, and this was the case in 40 samples that she said did not have the minimum amount of 1 nanogram of DNA evidence needed for a reliable result.

Of the 216 samples collected, Olckers received and analysed the data of 151 samples.

Earlier in the trial, State witness and chief forensic analyst Lieutenant-Colonel Sharlene Otto told the court that “no unknown DNA” had been found at the crime scene. She also told the court that the police forensic laboratory had had no problem finding DNA in any of the samples.

But, Olckers told the court that where there was not enough DNA, as in the case of 40 samples she identified, “whatever profile you get is invalid. Its wrong, its invalid and it should not be used”.

She said no female profile could be read into a DNA sample found in the shower. This was contrary to Otto’s evidence that a mixture of DNA profiles of brothers Rudi and Henri and the mother Teresa were found. Senior State prosecutor Susan Galloway said that to “prevent the guilty from going free and the innocent from going to jail” one would expect the Forensic Science Laboratory to go further than that. She referred to Otto’s testimony that 0.05 nanograms of DNA evidence is needed for a reliable result.

“You want the court to make a finding that these 40 samples must be ignored, yet you take those flawed results and make calculations from them,” Galloway said.