Tests have shown that a flex that was found around the body of Siobhán Kearney could not have held her weight for more than five to seven seconds, the Central Criminal Court was told yesterday.
The prosecution alleges that Ms Kearney was strangled and that an attempt was made to make her death look like a suicide by hanging her body from the door of her en-suite bathroom with a vacuum cleaner flex.
Dr Neal Murphy, a mechanical engineer and lecturer in UCD, who specialises in the stress and strain of materials, gave evidence of three tests he carried out in UCD last December on lengths of cable taken from the flex that was found around Ms Kearney's body.
A video of the three tests was shown to the jury.
The first test was carried out on a weight of 54kg, Ms Kearney's weight at the time of her death. It showed the cable break after approximately five seconds.
The second test was carried out on 42.4kg, which showed the cable break after 10½ minutes. The third test, on an intermediate weight of 47.4kg, showed the cable fail after seven seconds.
Dr Murphy told Denis Vaughan Buckley SC, prosecuting, that, on the length of cable that failed after five seconds, the internal copper wires were stretched out but the insulation sprang back into place. He said that there was "no significant whitening" of the cable, which was purple.
Dr Murphy was shown photos of the original flex as it was found around Ms Kearney's body.
He told the jury that the break in that cable was "similar in appearance" to the break in the length of cable that had failed after five seconds during the test carried out in UCD.
There was a "great difference in appearance" between the cable that failed after five seconds and the cable that failed after 10½ minutes, he said.
As a result of the second test, the purple insulation surrounding the cable became "much whiter in appearance". He said that this was "characteristic of the type of material which commonly whitens under stress".
Commenting on the photo of the cable which failed after 10½ minutes, Dr Murphy said: "Not only is it whiter, the insulation material has narrowed down". He said that this was because the cable "had time to stretch".
He told Mr Vaughan Buckley that if Ms Kearney had been suspended from the cable that was found around her body, she would have been suspended for "only five to seven seconds or thereabouts".
Dr Murphy agreed with Patrick Gageby SC, defending, that he had not been "invited to do a test in which the cable was doubled or in which the weight was partially leaning on something else".
The court also heard evidence from Dr Michael Norton, a forensic scientist.
Dr Norton told Dominic McGinn, prosecuting, that he examined the door to the en-suite in Ms Kearney's bedroom. He said that a section of the paintwork on the top edge of the door, on the side facing the bedroom, was damaged in the form of a "shallow groove", and that there was an area of purple material smeared into the damaged paintwork.
The purple material found on the door "matched the material covering the flex", he said.
Dr Norton said that he also examined the flex that was found around Ms Kearney's body and found an area of damage with white paint traces. The en-suite door was painted white, he said.
He told the jury that his conclusion was that the flex was in "forceable contact" with the top edge of the en-suite door when in an open position and that this was "consistent with a heavy weight or a body attached to the flex hanging over the door".
Dr Norton then demonstrated this scenario to the court with the en-suite door and with a reconstruction of the flex that was found around Ms Kearney's body.
Dr Norton also told the jury that, during his examinations, he turned the door upside-down and applied a flex to the edge. He said that he draped a flex across the door by light pressure and that there was no transfer of purple flex material onto the door.
With strong pressure there was no damage or transfer of purple material to the door, he said. He said that when very strong pressure was applied, there was an indentation caused on the paintwork but only on the side from which the pull was exerted. In addition, purple material was transferred to the door where very strong force was applied, he said.
Similar crossover happened on the purple flex, he added.
Dr Norton's conclusion was that it would have "required very strong pressure in order to make the marks that were found on the top of the door".
"A person of very small stature would have had to stand on an object to reach the height in order for the ligature to be placed around the neck. Someone would have to be 6ft 5in to do it."
Dr Norton said if somebody was in that position it would be "very difficult" to cause a second loop in the flex to go around the handle on the en-suite side of the door.
Earlier, he said that a second loop, which could have been used as an anchor, was five centimetres short of the door handle on the en-suite side.
He told Mr McGinn that the "unassisted hanging of Ms Kearney, given that she was 5ft 3in tall, was not feasible in light of the measurements of the flex".
Dr Norton told Mr Gageby that there was an alternative scenario in which the unassisted hanging of Ms Kearney was possible. However, he told Mr McGinn that in such a scenario, Ms Kearney's DNA would have been transferred to that area of the flex.