Update: 1pm Forensic evidence found on Corryn Rayney’s body could not be matched to samples taken from the Rayneys' Como home with the same certainty as fingerprints or DNA evidence, Lloyd Rayney’s wilful murder trial heard today.
The court was also told that marks on Mrs Rayney's jeans could have been made while she was being buried and were not necessarily incurred while she was being dragged, as a previous witness has suggested.
Peter Collins, principal chemist at WA's ChemCentre, agreed under cross-examination that the nature of the evidence recovered from Mrs Rayney's clothes and hair and examined by him, including paint and plastic particles, could not be matched 100 per cent to samples from the Rayneys' home.
For example he agreed that the only way an “unequivocal” match could be determined between paint samples was if the edges could be matched up.
The court heard yesterday that Mr Collins found “no significant difference” between paint recovered from one of the boots Mrs Rayney was wearing when she died and paint at the Rayneys’ home. That implies a match of more than 95 per cent.
The prosecution claim Mr Collins’ testimony supports their allegation Mrs Rayney was killed at home and her body likely dragged across her front yard. Other witnesses have given evidence about soil found on her body, which was also found to correlate to soil found at the Rayneys' home.
Mr Rayney’s lawyer Tony Elliot today asked Mr Collins if he was given the opportunity to survey the “wider area” outside the Rayneys’ home to “see how common this colour or types of paint were”. Mr Collins said he was not.
He said samples taken from the Rayneys' on several separate occasions were intended to provide "a reasonable and representative sampling of the paints" found at the home.
Asked if his approach when comparing paint samples was to look for differences between known samples Mr Collins said that was correct.
He also agreed with Mr Elliot’s assertion that the absence of significant differences “suggests that paints could have a common origin … not that they must have but that they might have”.
“(The results) definitely don’t say they must have (come from the same place),” Mr Collins said.
“There’s a degree of interpretation that can be applied to each of the fragments or group of fragments. Unless some material is universally distributed … (the results) support the proposition that they share the same origin.
“Really for each individual fragment or group of fragments there’s a different weighting for that proposition … none of them say they must have come from the sample (taken from the Rayneys’ home), that’s for sure.”
The court also heard about fibres found on Mrs Rayney’s body and near her Kings Park grave. Mr Collins said a red polyester fibre was found on the knee of her jeans and red “polyester thread” was found on the track near her gravesite.
Fibres were collected from the Rayneys' home.
Mr Collins said red and black fibres recovered from vegetation in Kings Park close to where Mrs Rayney was buried did not match clothing found at the Rayneys’ home. Nor could the fibres be matched to the clothes Mrs Rayney was wearing when she died.
However, two fibres found on Mrs Rayney’s shirt – but which did not come from the shirt – did match some of the fibres found in Kings Park.
Mr Collins referred to an apparent “snag point” in the bush where he said it appeared that a piece of wood hanging from a tree may have snagged “someone walking past” and caught some fibres.
Mr Collins was asked about what Mr Elliot described as the "oval marks" on the bottom of Mrs Rayney's jeans, saying he "didn't observe any damage" to the fibres of the jeans themselves. He said the marks were consistent with "pressurised contact".
Asked if the marks could have been made by the pressure of soil when Mrs Rayney was being buried Mr Collins said it was "probably a possibility". However, he added there were likely "many plausible explanations".
The court has previously heard from mineralogist Richard Clarke, who suggested the marks - which he described as V-like formations - could have been consistent with a "dragging event".