Defence advocate Barry Roux File photo: Siphiwe Sibeko

Pretoria - Her last meal was eaten two hours before she died, based on what was found in Reeva Steenkamp’s stomach. But then it could have been 11pm the night before. Or 3am that morning.

Experts are given a higher status in court than the dazed neighbour or the ex-girlfriend, but they too have limits to their testimonies.

Just as the neighbour can say it sounded like gunshots based on their previous experience of this sound, experts too give their opinions based on their accumulated knowledge. It’s not an exact truth.

On Tuesday, State pathologist Professor Gert Saayman used the example of trying to shoot a gun at a target on a wall. Most of the bullets would hit the same narrow area, but there will always be outliers.

“That (the narrow area) is where we concentrate as scientists, and from where we draw our references,” he said. “My evidence rests on a balance of probabilities.”

There could be one or two hours of variance either side of the last time Steenkamp ate.

Interpreting the contents of a stomach is not an exact science. The type and amount of food, posture and a person’s mental state could affect how quickly food is digested.

There is variation from person to person, and how one’s stomach works today might not be how it works tomorrow.

Oscar Pistorius has said in his affidavit that he and Steenkamp went to bed at about 10pm. So was he lying if it seems as if Steenkamp ate just two hours before she died?

Defence advocate Barry Roux on Tuesday produced a stack of journal articles which he placed in front of Saayman. One said that when given different foods in different amounts, people could take between 60 and 338 minutes to digest it. That’s a lot of variation.

Had Saayman seen these journal articles, and did they prove his evidence wrong?

Saayman said a fundamental issue of science was being dragged to the fore. If there was evidence to show one thing, and another, how do we decide which is correct?

A pathologist and honouree research fellow at the School of Law at the University of KwaZulu-Natal, Steve Naidoo, said it was in highly contested cases that either side might bring out research to emphasise their point.

The range in biological research could be so wide that it was rendered entirely useless, he said. So is there any point to these experts appearing in court?

Advocate Devina Perumal, a senior lecturer at the School of Law at the University of KwaZulu-Natal, said, although Saayman was an expert, his evidence was still his opinion.

“The court relies on the opinion of an expert because the court itself cannot make up its mind as the judge does not have this expert knowledge,” Perumal said.

She added that Saayman’s evidence was direct evidence while the journal articles were hearsay evidence, because the authors of the paper were not in court to testify on it.

Perumal said it was rare that a journal article was more valued over the direct evidence of a pathologist.

In support of this, Naidoo said: “If you speak to the author (of the paper), he or she would be the first to say they would respectfully yield to experience, and we have a tremendous amount of experience in this country.”

Perumal said the aim of bringing the papers to court was to discredit Saayman and cast doubt on his testimony. “They want to make him revisit his evidence by raising doubts on his own report.”

Pistorius’s pathologist, who attended the autopsy, might draw a different conclusion from the stomach contents.

Saayman’s testimony was based on 30 years of reading and personal experience from as many as 15 000 autopsies.

But even he was willing to concede that he would stand down to another more important piece of the puzzle.

“If there is any substantial evidence to the contrary, that must be weighed up by the court,” he added.

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The Star