A sentencing hearing in the US has heard audio of Thomas Martens 'chatting jovially' with detectives who were interviewing him about the killing of his son-in-law, Jason Corbett.
Thomas Martens and his daughter Molly have accepted a plea deal of voluntary manslaughter of the Limerick man.
Mr Martens pleaded guilty to voluntary manslaughter, while his daughter entered a "no contest plea", meaning she accepted the charge without an explicit admission of guilt.
Judge David Hall has said that a no contest plea is treated as a form of a guilty plea.
In return for their plea, the State of North Carolina has dropped the murder charges against the father and daughter.
Mr Corbett (39) was beaten to death with a baseball bat and a concrete paving slab in his Lexington home in 2015.
Jason CorbettIrish Independent Southern Correspondent Ralph Reigel told Newstalk Breakfast said the issue of self-defence is taking centre stage.
"The highest profile things that we've heard so far really surrounds the whole aspect of self-defence," he said.
"We've gone through the first audio recording of an interview that Tom Martens gave to police on August 2nd, 2015 - just a couple of hours after Jason Corbett was beaten to death.
"Mr Martens was quite outspoken, derogatory at times of Mr Corbett.
"He said that Mr Corbett had been drinking all day.
"He alleged that he had attempted to strangle his daughter Molly and that he had gone up and that when he confronted him, Mr Corbett then said that he was going to kill his American second wife.
"Mr Martens said that he struck him repeatedly with the metal baseball bat.
"He described his Irish son-in-law as 'crazy', he questioned whether it was only alcohol that he had consumed.
"He said at one point he feared not only for his daughter's life but for his own life.
"He said he kept hitting him until he went down".
Molly Martens and Thomas Martens. File photoMr Reigel said Mr Martens also joked with the officers interviewing him.
"There were times when Mr Martens became emotional in the interview," he said.
"Then the interview ended, actually, with Mr Martens chatting jovially - at times almost cracking jokes - about his time as an FBI Field Agent in Miami, Florida with two of the Davidson County detectives who were interviewing him," he added.
The charge of involuntary manslaughter can carry a sentence ranging from parole up to 17 years.
