Australian DNA expert Dr Brian McDonald admitted during cross-examination today that he may have made a mistake in his testimony by suggesting chemist Dr Seah Lay Hong had conducted acid phosphatase test on the nine cotton swabs taken from the complainant.

NONE This led to solicitor-general II Mohd Yusof Zainal Abiden ( right ) remarking that it was not a honest mistake, and that McDonald's evidence on the matter should be expunged.

Yusof made the assertion following a "misconception" during McDonald's examination-in-chief that Seah was wrong to conduct the acid phosphotase (AP) test on the nine cotton swabs taken from complainant Mohd Saiful Bukhari Azlan, including those retrieved from his rectum and peri-anal area.

McDonald had argued that for the AP test to be made, there must be semen in abundance and it should not be done on cotton swabs.

This led to Yusof reading out the notes of proceeding, which showed Seah conducted the PSA and sperm isolation tests on the nine cotton swabs and she did the AP test on Saiful's trousers and underwear.

Yusof: Seah conducted the AP test on the swab and you said it is not consistent with international literature?

McDonald: Yeah, it is not consistent as there must be semen in abundance (on the swab).

Yusof: I read the notes of proceeding, on page 868. Seah said on swabs B1 and B9 (retrieved from Saiful's body) two tests were used. The PSA and immuno acid tests were done to test the presence of semen. Seah said she only conducted the AP test on the clothing. How could you tell Seah said she should not do the AP test on the cotton bud? Where is your honesty?

McDonald: I am not sure. Honesty is not an issue here.

(There was laughter in the court, from the team of prosecutors).

Yusof: Could you have made a mistake in your testimony?

McDonald: Looking at it, it could have been a mistake, but this is unintentional.

Yusof: Can we consider to have that evidence expunged?

McDonald murmured something that could not be comprehended.

Yusof: I put it to you that you are trying to mislead the court.

McDonald: I was only making a comment as to how much semen (was there).

'Ideally, sample should be air-dried'

McDonald said it was unusual for one to obtain sperm after 56 hours and that this was a probability of one to 3,000.

dr brian mcdonald sodomy ll "That is what the literature says," added the Australian expert. "Ideally, the sample should be air-dried and frozen. I would place it in the freezer."

Yusof: When Dr Mohd Razali Ibrahim examined the recturm, there was no fluid and the peri-anal area was moist.

McDonald: I do not know.

Yusof: How long does it take to air dry the samples?

McDonald: It depends on one swab than the other. It depends on the moist. I cannot say how long it takes to air dry a swab. You do not put it directly in the container as you have to have it air dried first.

The witness said that samples should not be maintained at room temperature for fear that they would be contaminated by bacteria.

Freezing the samples would will stop the bacteria growth, and this could not be achieved by maintaining it at room temperature.

The Australian witness also said that from the sample, a slide to a receptacle should also be done so that one could view whether there was sperm at that time. Such a practice was based on international literature.

Yusof: Is it the medical doctor or forensic scientist who should do the slide?

McDonald: It should be the doctor. But the important thing is that you have to look at the slide to check and look at. What you get is you are able to look at when the sample was taken.

In this case, the samples were not frozen and no slide was done on them to verify this.

The trial resumes tomorrow morning with the continued cross-examination of McDonald.

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