Lawyers for Molly Martens Corbett and her father Thomas Michael Martens have told a court in the US that they have concerns for their safety.
Legal representation for Ms Martens claimed she had received threats on social media.
The allegations were made during a remand hearing for Ms Martens (32) and former FBI agent Mr Martens (65).
The pair have been charged with the second-degree murder and voluntary manslaughter of Ms Martens' husband, Jason Corbett (39), on August 2, 2015.
Limerick dad-of-two Mr Corbett was bludgeoned to death at his home in Panther Creek, North Carolina.
A post-mortem later showed he was beaten with an aluminium baseball bat and a paving stone.
The two accused have both entered pleas of not guilty, claiming self-defence.
During an administrative hearing at Davidson County Superior Court in Lexington, one of Ms Martens' lawyers, Walter Holton, voiced concerns that his client is receiving threats via social media.
Ms Martens and her father were each released on a $200,000 bond in January.
They were ordered to give up their passports and not to contact Mr Corbett's family, including his two children, Jack (11) and nine-year-old Sarah.
Jack and Sarah are the children of Mr Corbett and his late wife, Margaret Fitzpatrick Corbett, who died in 2006.
Mr Holton also claimed threats were made to Ms Martens' uncle and aunt, Mike and Mona Earnest.
Defence lawyers said they also are slightly concerned that the defendants may not receive a fair trial in Davidson County.
They claim this is due to the attention the case has received locally, the problems they claim to have experienced with the Davidson County Sheriff's Office and their motions against Davidson County Clerk of Court Brian Shipwash.
Ms Martens' attorneys accused the clerk of court and a lawyer representing her husband's estate with hiding unethical, secretive conversations about the case.
Within days of her husband's violent death, Ms Martens lodged an adoption application for the children.
A court ultimately decided they should live with the Lynch family in Ireland after hearing evidence from Mr Corbett's sister, Tracey.
Ms Martens and her father will next appear in court on May 30.