UPDATE: The man whose DNA was found on a cigarette butt outside the Rayneys’ Como home was living with a convicted sex offender, Lloyd Rayney’s wilful murder trial was told today.
Detective Sergeant Mark McKenzie, who was the second most senior officer in charge of investigating Corryn Rayney’s death, today gave evidence that police investigated both Ivin Eades, whose DNA was found on the butt, and convicted sex offender Allan Lacco, with whom Mr Eades was living at the time.
Det Sgt McKenzie said his investigation notebook included a note alongside Mr Eades' name with an abbreviation for "previous murder conviction".
The court has previously been told that a car driven by a person whose last name was given as Eades was stopped by police on August 7, 2007 - the night Mrs Rayney disappeared.
Det Sgt McKenzie also gave evidence the police found some of Mr Rayney’s behaviour after his wife disappeared suspicious, including how he "conducted himself in the media spotlight" and spoke to the media.
Phone calls between Det Sgt McKenzie and Mr Rayney were played to the court in which they discussed the investigation. However, Justice Brian Martin has yet to decide whether the content of those conversations is admissible as evidence.
Earlier a forensic expert gave evidence at least one and potentially two unknown male DNA profiles recovered during the investigation into Mrs Rayney’s murder could not be matched to any known person in a national database.
Laurance Webb said the DNA profiles, one of which was only partial, were recovered but could not be matched.
"The profile that we got was a weak DNA profile, there was an indication of a second person but at very low levels," he said.
"With unknown profiles… if there is enough genetic material… we will actually check against our own DNA database and the national database. So both of them were checked and there were no links to that particular profile or partial profile."
Taped phone calls between a police officer and Mr Rayney have been played to the court.
However, the defence has objected to the admissibility of the phone calls as evidence and Justice Brian Martin has yet to make a decision about whether they will be allowed.
The court also heard that a hair found on a towel in Mrs Rayney's car was DNA linked to Mr Rayney but the source of DNA on a handkerchief from the bottom of her grave could not be determined. Mr Rayney could neither be included nor excluded as a potential source of the DNA on the handkerchief.
Mr Webb gave evidence that his tests on the hair could not recover a DNA profile. However, tests by a UK scientist indicated a positive result for Mr Rayney's maternal line.
The differing results were explained by the fact Mr Webb was testing for so-called nuclear DNA, whereas the UK scientist was looking at mitochondrial DNA.
"This is not a surprising result," Mr Webb said. "There are a lot more copies of the mitochondrial DNA contained within the cell than nuclear DNA… and also they're more resistant to degradation."
The court heard that in cases where DNA evidence was present it was not always sufficient to determine a DNA profile. In some cases, for example, the evidence could only determine that it likely came from a man.
In cases where DNA was determined to have come from a particular person - for example DNA matched to Mrs Rayney from her car - Mr Webb said the match indicated there was a less than one in 10 billion chance the DNA could have come from someone else.
Under cross-examination Mr Webb said he agreed with evidence from another expert that DNA results taken from a street directory inside Mrs Rayney's car indicated "at least three individuals" although there was insufficient information to determine if Mr Rayney was one of those individuals.
If Mr Rayney was not a source of the DNA, it was possible there was DNA from at least one unknown male.
He also agreed that DNA evidence recovered from the CD button in Mrs Rayney's car and from Mrs Rayney's debit card indicated a male source that was not Mr Rayney.
The cigarette butt recovered from outside the Rayneys’ Como home which, the court previously heard was DNA matched to a person “well known to police”, returned briefly to the spotlight as Mr Webb gave evidence that the fact a full DNA profile could be recovered from the butt suggested it had not been there for a long period of time.
Similarly he said the level of degradation to the butt itself suggested it had not been exposed to the elements for long, although he could not give a time frame.
The cigarette butt was among items recovered from the footpath during a police search on August 22, 2007. Mrs Rayney went missing on August 7 of that year and her body was recovered on August 16.
The butt DNA matched a man known to the police who may have been in the vicinity of the Rayneys’ on the night Mrs Rayney died.
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