A jury found them guilty earlier this year of second degree murder of Irish man Jason Corbett
A US judge has refused to quash the convictions of the wife and father-in-law of Jason Corbett.
Molly Martens and her father Thomas were found guilty of the Limerick man's murder in a North Carolina court in August.
They had appealed to the Davidson County Superior Court to have their convictions quashed.
Ralph Riegel, Southern Correspondent with the Irish Independent, says the pair and their legal team had been claiming juror misconduct during the trial.
He explained: "Detailed legal submissions were made in support of that, including some affadavits from an alternate juror who had said he had seen or heard some of these discussions.
"Judge [David] Lee had taken effectively three months to discuss and examine the submissions made - and late last night he came out and rejected the defence applications."
The Winston-Salem Journal reports that attorneys for the Martens are planning to appeal Judge Lee's decision to the North Carolina Court of Appeals.
39-year-old Jason Corbett was beaten to death with a baseball bat and paving stone at his home in North Carolina two years ago.
He shared the house with his second wife, Molly Martens, and his two children from a first marriage.
Thomas Martens and Molly Martens were sentenced to between 20 and 25 years in prison after a jury found them guilty of second degree murder.