The prosecution in Oscar Pistorius' murder trial has challenged the credibility of an expert witness for the defence, which was trying to show that the athlete killed his girlfriend by mistake.
Roger Dixon was called to give evidence to support Pistorius' story that he killed girlfriend Reeva Steenkamp by accident thinking she was an intruder behind the toilet door in his home and about to attack him.
Pistorius is charged with premeditated murder for shooting Ms Steenkamp multiple times on February 14, 2013. Prosecutors say that he killed her after a fight.
The trial has been adjourned until May 5.
Continuing his cross-examination, prosecutor Gerrie Nel said Mr Dixon, the third witness to be called by Pistorius' defence, had no expertise in some areas where he was testifying and also had not been thorough in some of his examinations.
In one, the prosecutor criticised Mr Dixon, a geologist, for not using the exact height of double-amputee athlete Pistorius when standing on his stumps.
"It is something I omitted. I overlooked it at the time," Mr Dixon replied when questioned why his measurements were around 20 centimetres (eight inches) off in a test to see if Pistorius' head and body would have been high enough to be seen by neighbours through a bathroom window. He said he was not trying to "mislead" the court.
Mr Dixon is a former policeman and an expert in the analysis of materials at crime scenes. His testimony touched on ballistics, gunshot wounds, pathology and blood spatter, and he also said he was involved in audio and visual tests. He conceded he is not an expert in any of those areas.
The bearded university researcher was subjected to tough questioning by Mr Nel and has been ridiculed on social media and in the South African media for trying to be an expert in areas where he was not qualified.
Judge Thokozile Masipa will ultimately deliver a verdict. Pistorius faces 25 years to life in prison if convicted on the premeditated murder charge.