The Central Criminal Court has been told that forensic scientists did not find any traces of Brian Kearney's DNA on the vacuum cleaner flex found around his wife's body.
Mr Kearney denies murdering Siobhan Kearney at their home on 28 February 2006.
This morning the court heard evidence from Dr Dorothy Ramsbottom from the Forensic Science Laboratory at Garda Headquarters.
She gave evidence of examining swabs taken from the vacuum cleaner flex and examining the flex itself to identify possible sources of bodily fluids or cells if present.
In her first report, she said she had found samples of Siobhan Kearney's DNA and of a male component, which had a 1 in 18 chance of matching Brian Kearney's DNA.
However when she re-examined the vacuum cleaner flex using a more sophisticated technique which was not in use in 2006, she found that the male sample discovered did not match Brian Kearney's.
Further tests carried out to compare the male sample to firemen and gardaí who arrived at the scene found that one fireman and one garda could not be eliminated as a possible source of the sample.
Asked by prosecution counsel Denis Vaughan Buckley if it was possible for someone to handle an item and not leave a DNA sample, Dr Ramsbottom replied that it was.
