UPDATE, 4.15pm Soil and brick particles found in the liquidambar seed pods recovered from Corryn Rayney's hair were "consistent" with those found outside the couple's Como home, her husband's Supreme Court murder trial was told today.
The mineralogist who examined the pods, as well as soil found in and on Mrs Rayney's car, boots and clothes, also testified that brick powder found on her boots indicated her body may have been "drawn across" a brick surface, causing "traumatic" damage to the boots.
Richard Clarke, a research mineralogist at WA's ChemCentre, spent the day giving evidence about similarities between the soil, red brick particles and microscopic sprigs of moss found on Mrs Rayney's body and samples taken from the Rayneys' home.
Mr Clarke's evidence is relevant to the prosecution's case because they claim Mrs Rayney was killed at her home and her body likely dragged across the brick paving and into the backseat of her car. The prosecution alleges the seed pods came from the liquidambar tree outside the Rayneys' home, while the defence has attacked the forensic integrity of the pods and questioned when and how they were recovered from Mrs Rayney's body.
At several points during lengthy cross-examination Justice Brian Martin appeared to become frustrated with the direction of questioning, saying the court was "not here to skirt around issues".
Mr Clarke said he found moss inside at least one of the seed pods and observed similar moss on brick paving taken from the Rayneys'. By comparison he said there was a "vast difference" between it and moss found elsewhere at Kings Park, where Mrs Rayney was buried in a clandestine grave.
Moss was also found on Mrs Rayney's boot, the doorstep of her car and on the clothes she was wearing when she was killed. Mr Clarke said he was "fairly confident" he had identified a red paint particle on a pod, but the particle was lost when he attempted to recover it.
Mr Clarke described soil recovered from at least one seed pod as 'consistent" with the "indigenous soil" found outside the Rayneys' home.
Brick particles found on the heel of Mrs Rayney's boots suggested they had made contact with a hard surface – "presumably brick" and subsequently been "drawn across" that surface, he said.
"The direction and motion indicated... are consistent with the face of the heel being in contact with a brick surface or a soil-covered brick surface as the victim was drawn backwards," he said.
"I'm not implying a time frame but (this action) must have been very late on in the history of the boot because otherwise these grains would have been removed relatively easily by normal wear."
Mr Clarke said he believed the marks on the heels of Mrs Rayney's boots were caused by "some kind of traumatic incident" instead of "general wear and tear".
"There's a big contrast in the condition of the heel... compared with most of the rest of the boot," he said. "So if we have what's called general wear and tear you'd expect damage to all of the boot, not just a localised area of the boot."
Asked why more soil from Kings Park was not recovered from Mrs Rayney's body Mr Clarke said the soil consistent with that found at the Rayneys' home had likely adhered particularly well to the seed pods because the pods were "located in a wet area... on an uneven brick surface and had been subjected to wetting and drying”.
Earlier the court heard the seeds were covered with "substantial amounts of sandy soil", with traces of brick particles, fibres and hair, including one or more human hairs, when Mr Clarke first examined them in March 2008.
The court also heard details of Mr Clarke's method in determining the difference between apparently similar sandy soils common around Perth, which he said involved identifying coatings on specific soil particles.
Mr Clarke said he had worked with Perth soils since 1972 and for more than 20 years with a particular method that involved using x-ray diffraction to examine soil particles. He said the method, which is not universally used, made it possible to distinguish between samples where there was a similarity of sand grains but a dissimilarity of coatings.
"The methods you use to (examine) soils are dependent on the nature of soils," he said. "We have particular issues here with our sandy soils. If you to Brisbane, for example, you've got predominantly clay soils... and the methods of obtaining the samples and analysing the samples might be different.
Mr Clarke's evidence was observed, via videoconference, by a UK-based defence witness.