Dr Antonel Olckers, a DNA expert and the defence's first witness to be called in Henri van Breda triple murder trial. Picture: Catherine Rice/ANA

Cape Town - The defence's DNA expert in the trial of alleged axe murderer 22-year-old Henri van Breda faced heavy criticism in the Western Cape High Court on Thursday, as the State wrapped up 4 days of grueling cross-examination.

Senior State prosecutor Susan Galloway told the court that in two cases in which the defence solicited the opinion of Dr Antonel Olckers, the judgments had criticised her findings.

In one of the cases, the judgment referred to the "paucity of Olcker's practical experience" as well as the lack of her statistical knowledge. Galloway pointed out that Olckers still has "very little practical experience in a forensic laboratory".

But, Olckers said she disagreed in the "strongest possible terms": "I have worked my entire life in a molecular biology lab". 

Judge Siraj Desai, who has this week consistently urged her to keep her answers short, said "the simple point is you never worked in a forensic laboratory".

Galloway told the court that in a case dating back to 2004, Olckers had had similar criticisms of processes followed in the laboratory as she has had in this case, yet the state's evidence was accepted. Despite some "non-conformances" the court found that the data could not be invalidated. 

Galloway has also attempted to show the court that Olckers's experience consisted of mostly “administrative and academic positions”.

Olckers was hired by Van Breda’s defence team to test the validity of DNA evidence presented by state witness and chief forensic analyst at the police’s forensic laboratory, Lieutenant Colonel Sharlene Otto.

Van Breda faces three charges of murder, one of attempted murder and one of defeating the ends of justice for the January 2015 axe attacks on his family at their luxury home in a security estate in Stellenbosch.

He has pleaded not guilty to all the charges.

Instead, he claims that after a fight with an axe-wielding intruder who was also armed with a knife, the man had escaped. Otto, however, who analysed 216 samples from the crime scene, testified that “no unknown DNA” had been found.

Last week, Olckers told the court that she received analysis of 151 DNA samples out of the 216 taken from the crime scene. 

Olckers contended that standard operating procedures had not been followed and a breakdown in three processes in particular invalidated the analysis.

She told the court that samples from the same case shouldn’t follow each other on a laboratory work list, yet this had happened with 116 samples in this case, raising the chance of cross-contamination.

But, when Galloway on Thursday asked her if she had found any "actual contamination" she responded: "Did I definitively pick up contamination, I cannot say". Judge Desai, visibly frustrated by her avoiding simple yes or no answers, asked the State to move onto their next question.

In earlier testimony, Olckers also told the court that there were 32 DNA samples where the expiration date of Hemastix, used in presumptive testing for blood, was not indicated. She testified that it cannot be used once expired.

On Wednesday, Olckers told the court that there was not enough DNA in 40 samples taken from the crime scene to yield scientifically valid results.

She said that “one cannot make a valid conclusion from an invalid interpretation” and this was the case in 40 samples, which she said did not have the minimal amount of 1 nano-gram of DNA evidence needed for a reliable result.

On Thursday, Olckers's criticism of standard operating procedures in the other two earlier cases she had been involved in prompted Judge Desai's observation: "The simple point is this - the minute you feature, there is a great deal of discovery that the state has to do. You first find out everything, and then dispute the chain of evidence as a scientist". 

Olckers replied that she requests the full paper trail in every case and found it "quite alarming that these issues persist, a system should be put in place so these errors don't occur".