The uncle of Molly Martens, charged with the murder of her Limerick-born husband Jason Corbett, is reportedly being investigated for attempting to gain access to Corbett’s office the day after his murder.

Mike Earnest, Martens’ maternal uncle who works for a US federal law enforcement authority called Special Inspector General for Afghanistan Reconstruction (SIGAR), is being questioned regarding alleged calls made to Corbett’s workplace, Multi-Packing Solutions, attempting to gain access to the office and telling staff he was a federal agent, Irish website report.

Although Earnest denies that he is under investigation, his employer SIGAR confirmed they were investigating contact he made with MPS on August 3.

“SIGAR is conducting an administrative inquiry. We take all allegations seriously and review them thoroughly. Since this is a personnel matter we cannot comment further,” a spokesperson confirmed.

Originally from Limerick, Corbett, 39, moved with his American wife Martens, 32, and his two children from a previous marriage, Jack and Sarah, to North Carolina in 2011.

He was found unconscious in his home with a fatal head injury on August 2, 2015 by police investigating an emergency call about a domestic disturbance in the early hours of the morning.

A transcript of the 911 call that was made has since been released and during the call Martens' father, former FBI agent Thomas Martens, 69, admitted hitting his son-in-law with a baseball bat.

Both Molly Martens and her father have been charged with the second-degree murder and voluntary manslaughter of Corbett but are claiming self-defence. They were released on bail but told not to attempt contact with the children.

Martens’ uncle is now also believed to be under investigation for alleged attempts to enter Corbett’s office at MPS claiming he was doing so as part of his role as a federal agent. After staff contacted police regarding the call he was refused access. alleges that the children's passports were in the office.

It is believed that Earnest also accompanied Martens to the office on August 4, two days after the death, as she collected her husband’s possessions as next of kin.

Earnest has denied the claims, stating that he does not believe he made any calls to the plant but that he and his wife had made a lot of phone calls on the day following Corbett’s death in assisting his niece to organize funeral arrangements, insurance and arrangements for the children. He believes that if he did make a call to the workplace then it would have been a “diplomatic” call about the death.

When questioned particularly about attempting to use his position as a federal agent to gain access to the office, Earnest strictly denied the claims.

“That is a complete lie and fabrication. There could be nothing further from the truth,” he said.

“‘It’s one thing to tell a lie about an average citizen. It’s another to tell a lie about a sworn US federal agent.”

In the days immediately following his death, custody of Corbett’s two children was in dispute. Although Corbett's had named his sister Tracey Lynch and her husband David Lynch as the children's guardians in his will, they were initially denied access and the children remained under the guardianship of Martens and her family.

In the course of a bitter custody battle between the widow and Lynch, Corbett's sister claimed that Martens displayed volatile anger and was obsessed with Corbett’s children, especially Sarah. In August 2015 the children were placed in the custody of Lynch and her husband and they all returned to Ireland.

Martens has since vowed to win custody of the children, filing a notice of appeal with North Carolina's Court of Appeals last month. Her initial appeal failed on December 8, 2015.

Corbett and Martens married in 2011 after she was hired as his fourth au pair for the children in 2008. His first wife died following a severe asthma attack in 2006.

Corbett and Martens became romantically involved and moved to North Carolina where Corbett worked for a pharmaceutical company, MPS.

The Irish Independent reports that during the custody battle it emerged Martens sought legal advice in 2013 regarding her legal rights to the children in the event of a divorce. She spoke further on this matter with an attorney in 2014.

It is also reported that Corbett planned to return to Ireland with his children but without Molly in the coming year. His family has spoken strongly about Molly’s behavior and claimed she was a “liar” and a “fantasist.”

Although Thomas Martens claims he hit Corbett while breaking up a fight between the married couple in which Corbett was strangling his wife, neither of those charged showed any sign of injury and it is now believed the baseball bat used may not have been a present for Jack not yet given to his step-grandson, as claimed, but a bat that was kept in the couple’s garage. A concrete block was also used to hit the victim.