Killer shot victim in head at point-blank range, court told
Father-of-one Kenneth O'Brien died from an "instantaneously fatal" gunshot wound to the head that caused extreme skull fractures and catastrophic brain injuries.
The muzzle of the gun was pressed against Mr O'Brien's head when it was fired, a pathologist said.
His head and limbs had been "neatly cut" off his torso, but the dismemberment was "crude" and did not display any anatomical knowledge.
Deputy State Pathologist Dr Michael Curtis was giving evidence in the Central Criminal Court trial of Paul Wells.
Mr Wells (50), of Barnamore Park, Finglas, has pleaded not guilty to murdering Mr O'Brien (33) at that address between January 15 and 16, 2016.
He has admitted that he shot him dead, but said it happened when they struggled during a row after Mr O'Brien turned up at his home with a gun.
The accused claimed that Mr O'Brien had wanted to have his partner Eimear Dunne murdered and Mr Wells refused to do it.
He said he "panicked" and chopped up the body in his back yard with a chainsaw, throwing the torso in a suitcase and the head and limbs in bags into the Grand Canal near Sallins in Co Kildare.
Dr Curtis said he carried out a post-mortem on Mr O'Brien's torso, which was found on January 16, 2016, then on nine further body parts found more than a week later, on January 24.
He noted the head had been cut off at around the sixth vertebra. The neck and limbs were "neatly sawn across ... consistent with the use of a power saw".
The body, he said, was relatively well preserved.
The jury was told that two Tesco and two Dunnes Stores bags were found with the handles knotted and further plastic bags inside, bound with cable ties, containing body parts and bricks.
One bag contained the arms in four sections; the legs, also in four parts with the feet attached, were found in two more bags, and a fourth bag contained the head. The hands were not recovered.
One of the upper arms had a tattoo with letters, possibly the word 'Ken', the jury heard.
Dr Curtis said, he had found a bullet entrance wound on the back left of the skull, tracking "directly forwards and very slightly downwards".
The injury was a "contact entry wound", he said, and "the muzzle of the weapon has been pressed against the head and all the products of discharge have gone into the head".
The skull bones were extensively shattered and the bullet had rebounded back into the cranial cavity, remaining in the head, along with its jacket.
The brain was "severely traumatised", he said.
Dr Curtis said there were extreme skull fractures and catastrophic brain injuries "which would have proved instantaneously fatal".
In cross-examination, Dr Curtis agreed with Michael O'Higgins SC, defending, that there was "nothing to indicate the person dismembering the body displayed any anatomical knowledge" and "the cutting was crude".
The trial continues.