Updated, 3.30pm: The question of whether Corryn Rayney’s body was or was not dragged across the Rayneys' brick-paved front yard was front and centre at her husband’s Supreme Court murder trial today.
Under cross-examination today mineralogist Richard Clark said subsequent findings did not necessarily support his original belief that Mrs Rayney’s body was dragged backwards across a hard, soil-covered surface.
Instead he gave evidence that the forensic evidence - which included soil samples taken from Kings Park, where she was buried - suggested there may not necessarily have been a hard surface involved, only a soil-covered one.
Asked if he could say that Mrs Rayney’s boots had been dragged across the Rayneys’ brick-paved front yard Mr Clarke said: "Not with certainty, no".
However, he said markings made on Mrs Rayney’s jeans still appeared “extremely convincing” as an indicator of a dragging event.
In a sign of how big a role forensic evidence will play in the State’s case against Mr Rayney, today marked the third day Mr Clarke has given evidence.
Mr Clarke, who works at WA’s ChemCentre, has given extensive evidence about the soil, brick, plastic and moss particles found on Mrs Rayney’s boots and the liquidambar seed pods recovered from her hair.
Prosecutors allege soil and brick particles found on Mrs Rayney’s clothes and liquidambar seed pods recovered from her hair prove she returned home after her bootscooting class on the night of August 7, 2007 and was killed there.
They claim Mr Rayney dragged her body across their brick-paved yard and into the backseat of her car, which he drove to Kings Park and buried her.
The defence has attacked the integrity of some of the forensic evidence, particularly the seed pods, and the police investigation.
Earlier Justice Brian Martin questioned Mr Clarke about how a “gouge” mark on Mrs Rayney’s left boot may have been created, asking if it could have been caused by her boots “moving forward”
Mr Clarke’s previously gave evidence that the particles in the gouge mark suggested the boot was dragged backwards but he has not explained how the mark itself was caused, other than suggesting frictional forces were responsible.
“What about the boot moving forward? Could you explain that gouge and the presence of the quartz grain with the boot moving forward,” Justice Martin said.
Mr Clarke said it was “hypothetically” possible but he said the quartz grain found in the gouge mark on Mrs Rayney’s boot was unlikely to have caused the gouge mark itself. He said it was more likely “a stone or something larger” had caused the mark.
Under cross-examination from Mr Rayney’s lawyer Tony Elliot, Mr Clarke said that when he received the boots they were packaged in double-sealed plastic bags. Among the soil material on the boots Mr Clarke noted a “suspected animal hair”, but the hair was not tested.
Mr Elliot also questioned why Mr Clarke had not taken soil samples from the Bentley Community Centre, which was where Mrs Rayney was last seen alive.
“I’d already examined soil from the tips of the boots and it was quite clear to me from examination of those materials that we were looking for a location, a source, which contained an assemblage of soil and brick particles,” Mr Clarke said in response.
“And my interpretation is that they would have been picked up from a… brick-paved area where there was also soil and that soil would contain associations of brick particles and paint and plastic.
“My visit to Bentley suggested there was no area of red brick that could have given rise to the particles I saw in the soil… there was no evidence of soil on the bricks (at Bentley) – they were relatively free of sand or organic matter and so I didn’t consider this was a possible source area for this soil.”
Mrs Rayney’s boots were found in the back of her car. The prosecution has claimed they were likely removed to make it easier for her body to be dragged through Kings Park to her grave.
Separately the court was told Mr Clarke did not consider Mrs Rayney’s car to be a useful source of information for examination.
"We found three seeds on the body, those seeds were associated with soil material that we matched with (the Rayneys’ home) - they were found in the hair or in the body bag," Mr Clarke said.
"And yet no additional seeds were recovered from the car."
He said Mrs Rayney’s body would have to have acted as a "seed magnet" to pick up the sole seed pods in the car, something he said would "defy logic".
He said glitter of "the sort... you get on novelty hats" was found in the car but not on Mrs Rayney.