Hair strands and to whom they belong were the main points of contention in Henri van Breda's trial for murdering his parents and brother and failed attempt to murder his sister.
The De Zalze family axe murders took place in January 2015.
On Monday, Henry Stewart, a police forensic analyst trained by the US Federal Bureau of Investigations (FBI), gave evidence about strands of hair he had analysed.
Van Breda's lawyer, Pieter Botha, interrogated apparent discrepancies in Stewart's testimony in the Western Cape High Court.
Stewart had testified that he had been sent hair to analyse, but did not know to whom the hair belonged until he was subpoenaed.
But Botha questioned this, saying there were two instances where Stewart had to have been aware that the hair was from the Van Breda family.
It was revealed in court that Marli van Breda, who was severely injured in the attack, had been clutching hair when she was found by paramedics.
Stewart had said that the hair in her grasp had initially borne resemblance to the reference evidence which matched Henri Van Breda.
He also said that hair cannot be used to identify connections in a case in the same way that DNA evidence can.
Rather, the hair could be used in conjunction with other DNA evidence.
Botha questioned how the connection could be made to Henri by the hair that was in Marli's grasp, saying that photographic evidence showed the hair in question to be about 10cm long while Henri's hair was about 3cm long at the time.
Stewart agreed that the hair looked different to Henri's but it could tell a different story under a microscope.
Botha also questioned why Stewart had failed to mention in his initial report that there were hairs found on the scene that did not correspond to the Van Breda family.
Stewart's cross-examination is due to continue on Tuesday morning.