UPDATE, 12:49pm Lloyd Rayney's WA Supreme Court trial was offered an insight into the way in which forensic police officers collect and handle exhibits in the course of a murder investigation in court today, as Mr Rayney's defence team continued to attack the credibility of the police investigation.
And the court heard more details of the police investigation, including that two vacuum cleaners at the Rayney's home were examined and their contents photographed but police found "nothing of interest".
Senior Constable Scott Walker, a key forensic exhibits officer who took two liquidambar seed pods found in Corryn Rayney's hair to the WA Herbarium for examination by experts, was also questioned by Mr Rayney's defence lawyer David Edwardson about why some of the exhibits in Mrs Rayney's case were labelled out of order.
Sen Const Walker said the most likely explanation for having non-sequential exhibit numbers was that the officer who was entering the exhibits into the computer system might have "gone for a cup of tea" or "gone to the toilet" and the sequential numbers were used by another officer who was on the system at the same time.
Mr Edwardson questioned Sen Const Walker about a missing tamper-proof seal from the paper bag containing the seed pods and his interactions with one of the experts who examined them. Sen Const Walker said he could not explain why the original seal placed on the bag in August 2007 was missing from a photograph taken of the bag in October of that year.
Mr Edwardson also suggested Sen Const Walker failed to take gloves and masks to the herbarium with him as he had previously told the court. Sen Const Walker rejected the assertion.
The defence have spent much of this week attacking the credibility of the forensic police investigation. In particular they have questioned the credibility of the evidence about the discovery of the liquidambar seed pods.
The seed pods are crucial to the prosecution's case because they claim their presence proves Mrs Rayney went back to her Como home on the night she was killed. They allege the pods came from the liquidambar tree outside the Rayney's home.
Walking the trial through some of the standard procedures used by forensic officers, Sen Const Walker described the way in which exhibits were treated to avoid cross-contamination.
"Once the exhibit is placed in a brown paper bag, in this instance, the bag is folded and then sealed using sticky tape," he said.
"An evidence seal is then placed across that fold where the tape is. On that exhibit seal the officer will then sign his name and write his regimental number… and the officer will then date it."
He said exhibits were assigned item numbers generally based on the police officer's initials and the order in which the exhibit was received.
Senior Constable Deborah Freegard was also called to give evidence to the trial today - the latest in a long line of police officers to be called as a witness in recent days.
She was asked, among other things, about a series of photographs taken inside and outside the Rayney's Como home. Sen Const Freegard took photos of a shed at the rear of the Rayney's property and upstairs and downstairs inside the house.
Photos of Mrs Rayney's boots were also produced. The boots, which Mrs Rayney was wearing at her bootscooting class on the night she was killed, were found in her abandoned car. The prosecution allege they were likely removed before she was buried to make it easier for her body to be dragged through Kings Park to her grave. Soil particles found in the soles of Mrs Rayney's boots form part of the prosecution's forensic case.The prosecution tendered four volumes of photographs taken by Sen Const Freegard on August 22, 2007 to the court.