Jason Corbett may have sustained the first blow to his head while he was in or beside his bed in his North Carolina home, a court has heard.
A forensic scientist said blood spatter marks indicated retired FBI agent Thomas Michael Martens (67) was standing above Mr Corbett (39) when the Irish businessman's skull was struck with a metal baseball bat.
Dr Stuart James told a Davidson County murder trial he found blood spatters on the inside of the quilt on Mr Corbett's bed, in addition to blood saturation marks inside the mattress. He said they may well have been from the first blow struck.
The Florida-based expert examined the home where Mr Corbett suffered at least 12 heavy blows to his skull.
Dr James also said a careful analysis of the multiple blood spatters and stains in the bedroom, hallway and bathroom of Mr Corbett's Panther Creek home indicated that, at one point, the father of two suffered multiple blows as he was falling to the ground. Critically, Dr James noted that, in one area, blood patterns indicated Mr Corbett's head was impacted as he was falling to the ground.
The revelation came as a former US federal agency co-worker of Mr Martens also testified that he commented on how he "hated" his Irish son-in-law. The comment was passed just two months before the death of Mr Corbett.
The evidence was heard in the North Carolina trial of Mr Martens and his daughter, Molly Martens-Corbett (33), who both deny the second-degree murder of Mr Corbett on August 2, 2015.
Dr James, who has written a book on the analysis of blood patterns, is considered one of the top US experts in the field.
The Florida-based expert studied blood spatters found on the red Izod polo shirt and white patterned boxer shorts of Mr Martens and the blue patterned pyjama suit of Ms Martens-Corbett worn on August 2.
Dr James said blood spatters on the inside lower hem of Mr Martens's boxer shorts were different in direction from those on the front of the underwear. He said it was consistent with Mr Corbett's head possibly having been close to the bedroom floor.
Mr Corbett died from multiple blows to his skull. These were inflicted by a 28-inch Louisville Slugger baseball bat and a stone garden paving brick. The blows were so violent and caused such damage to his skull that pathologist Dr Craig Nelson could only estimate that Mr Corbett suffered at least 12 blows.
Mr Martens and his daughter have argued self-defence. The former FBI agent claimed that he interrupted a dispute between his daughter and his son-in-law early that morning in which Mr Corbett was allegedly trying to strangle the woman. Mr Martens said he struck Mr Corbett with a baseball bat to defend both himself and his daughter.
The trial also heard yesterday that Mr Martens told a former co-worker in a special security unit of the US Department of Energy that "he hated Jason" and also had disdain for his son-in-law's Irish family.
Joanne Lowry worked alongside Mr Martens in the US Department of Energy for a decade. Both were co-workers in a security unit which specialises in counter-intelligence.
Assistant District Attorney Alan Martin said the proposed evidence was relevant in that it went towards potential malice as required by the second-degree murder definition.
Ms Lowry said that it was "common knowledge" in the Oakridge unit in Tennessee that Mr Martens disliked his Irish son-in-law and his family. Ms Lowry said Mr Martens expressed his dislike for Mr Corbett in a general conversation.
"He said the children were down [for the weekend]. He said: 'You are always glad to see them come, but you are always glad to see them go.'
"[He said] 'That son-in-law - I hate him.' He was in a pretty good mood - 'til he commented. There and then his mood changed."
The trial continues.
Jurors in the Jason Corbett (39) murder trial in North Carolina were today shown the baseball bat and blood-stained garden paving brick used to inflict fatal head injuries on the Limerick father-of-two.
A NORTH Carolina crime scene examiner had to repeatedly ask Molly Martens Corbett (33) to stop rubbing and tugging at her neck as she stood outside the home where her husband, Jason Corbett (39), was found with fatal head injuries minutes earlier.