A principal mineralogist yesterday said microscopic analysis of sand and brick particles on Corryn Rayney's boots indicated they were "drawn" backwards along a brick surface in a recent "traumatic incident".
Richard Clarke, of WA's ChemCentre, yesterday told Lloyd Rayney's wilful murder trial he believed "striations" in the heel area of Mrs Rayney's leather boots that held quartz grains and red brick dust were not the result of general wear and tear.
Prosecutors claim analysis on soil and artefacts, including red brick particles, found on Mrs Rayney's clothes and in liquidambar seed pods from her hair and body bag show she was killed at her Como family home after returning from a bootscooting class on August 7, 2007.
Her body was then allegedly dragged by her estranged husband through the brickpaved yard and driven to Kings Park, where she was buried shoeless. Her boots were found in her dumped car.
Mr Rayney's defence team has suggested problems with the "integrity" of the seed pods and flaws in the police handling of exhibits.
Yesterday, Mr Clarke showed super-magnified images of soil, brick, moss and paint particles found on the boots and in the liquidambar seed pods, which the State claims came from a tree at the Rayneys' home. The Supreme Court was told Mr Clarke's analysis involved reducing some particles to less than a 20,000th of a millimetre to determine the "coatings" of sand grains for comparison.
The mineralogist said soil from inside one of the pods was consistent with "indigenous" soil from the front lawn at the Rayneys' Como property.
Photographs of minuscule moss sprigs found on Mrs Rayney's clothes, brick paving at her home, and from Kings Park were also shown, with Mr Clarke suggesting a "vast difference" between the moss from the Como property and the Kings Park sample.
There were "many correlations" between the mineral components found in powdered brick remnants from inside one of the pods and brick particles taken from the Como property, he said.
Mr Clarke suggested diagonal scratches on the boots contained bits of quartz which became stuck as the boot was drawn backwards along a soil-covered brick surface with some force, with the quartz grazing the brick and gathering brick powder in the scratches.
He suggested the heel damage was a result of a "traumatic incident" that was "recent" in the boots' history given the quartz particles had not yet dislodged.
He said a lack of overall damage on the boots suggested the heel striations were not from general wear and tear.
Mr Clarke agreed under defence questioning that quartz grains were found all over the Perth basin.
He said he had not believed testing organic matter found in the soil was necessary for his conclusions.