Thomas Martens and Molly Martens-Corbett have been found guilty of the second-degree murder of Irish man Jason Corbett.
Both have been sentenced to 20-25 years in prison.
Judge David Lee recommended that Martens-Corbett received psychiatric treatment following her conviction.
Mr Corbett, 39, was killed in his home in Wallburg, North Carolina on 2 August 2015.
Both Martens-Corbett, who was married to Mr Corbett, and her father Thomas Martens had pleaded not guilty, claiming self-defence.
The wife and father-in-law of Irish man Jason Corbett have been found guilty of second-degree murder pic.twitter.com/bQASdyWJUb— RTÉ News (@rtenews) August 9, 2017
Mr Corbett died from head injuries. In a 911 phone call released last year, Martens admitted hitting him in the head with a baseball bat.
Martens told the emergency line operator: "He’s bleeding all over. I may have killed him."
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Both families and Martens-Corbett quietly sobbed as the verdict was announced.
Martens remained expressionless as he exited the courtroom in handcuffs.
The pair were remanded during a 15-minute recess immediately following the verdict.
Those in the court room were cautioned prior to the verdict not to disrupt proceedings.
As Martens-Corbett was led out of the courtroom in handcuffs, she quietly managed to say through tears, "I'm sorry, Mom."
Second-degree murder is defined as an intentional killing that was not premeditated.
The pair had also been charged with voluntary manslaughter.
Notes of appeal issued were issued by attorneys for both Martens-Corbett and Martens.
Originally from Limerick, Mr Corbett is survived by Sarah and Jack, his two children from his first marriage.
His first wife, Mags, died from an asthma attack in 2006.
He set up the Mags Corbett Trust following her death, which raised funds for the Asthma Society of Ireland.
Mr Corbett married Molly Martens in 2011 and moved to Wallburg, North Carolina the following year.
Jason Corbett - Limerick man, husband, father, friend and philanthropist pic.twitter.com/OA8xBahsxU— RTÉ News (@rtenews) August 9, 2017
Assistant District Attorney Alan Martin read a letter from Jack Corbett to the court.
"My father’s death has been life-changing for me," Mr Martin read aloud.
"My dad was always there for me, always cheering me on in sports, in school and everyday life. I always hoped after that night he could see me score a goal in rugby. … But he won’t be there.
He won’t be there for me if i marry or have kids. He’ll miss everything. He won't see me grow from a child to a teenager.
"I can never go to movies or pass a pass without feeling bad because that’s what me and my dad did. We are now seen as the family of the Irish man who was killed in his home (in North Carolina) … by a murderer named Molly Martens," the letter continued. "One thing she is not and never will be is part of the Corbett family.
"My dad will not be forgotten," Jack’s letter concluded.
Molly Martens will also never be forgotten. She will be known as the woman who murdered her husband for no reason.
The prosecutor struggled to maintain control his emotions as he read the statement. Multiple times, he fought back tears as he spoke and seemed affected by the young man’s sentiments. He was equally as emotional when he gave his opening remarks to the court earlier in the morning.
"There is no joy, there is no triumph, there is no pride," he read in a prepared statement on behalf of the Corbett family and the prosecution. Mr Martin’s voice cracked and wavered as he continued. "There is only grief."
A sister of Jason Corbett speaks outside the court house after his wife and father-in-law were found guilty of second-degree murder pic.twitter.com/e4ndlzON9o— RTÉ News (@rtenews) August 9, 2017