The claims were made during a fierce custody battle in August 2015 as Lynch and her husband, David, fought to take the children, a boy (11) and a girl (9), from their stepmother Martens and return with them to Ireland.
Originally from Limerick, Corbett, 39, moved with Martens, 32, and his children to her home in North Carolina following the death of his first wife from an asthma attack.
After their father’s death, the children were initially placed in Martens’ custody, then named as a “person of interest” in the victim’s death, until Corbett’s family won a custody battle to raise the children in Ireland.
In newly released court documents from the custody case, Lynch accused the widow of obsessive and volatile behavior, claiming she had an obsession with making the children call her “Mom”.
Lynch also claimed that Martens had displayed “explosive anger” towards the children, at one point putting the boy’s head in a sink while water ran into his mouth because he splashed her at a family outing.
Martens denied these claims during the case but Tracey and David Lynch were named the children’s guardians.
Corbett was found unconscious in his home in North Carolina on August 2 by police investigating an emergency call about a domestic disturbance in the early hours of the morning.
He had received fatal head injuries, believed to have been caused by a baseball bat found at the scene. Both Martens, and her former FBI agent father, Thomas Martens, 69, were named as “persons of interest” in the murder, and police announced they were not looking at suspects outside of the home.
It has been reported that Thomas Martens was the person to make the 911 call, allegedly telling local police he hit his son-in-law with a baseball bat in defense of his daughter.
Marten and her father were this week charged with the second-degree murder and voluntary manslaughter of Corbett. They claimed they acted in self-defense and have been released on bail.
The children initially remained in the care of their stepmother Martens following their father’s death, despite Corbett’s will outlining that they should be placed in the custody of his sister, Tracey Lynch.
Traveling to the US, Lynch was initially refused access to the children and Jason’s funeral was postponed until they were returned to the family.
In late August 2015, the judge ruled that the children could return to Ireland with Lynch.
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.
It has previously been reported that Martens had sought legal advice regarding a divorce and custody of the two children two years ago, although her lawyers state that she never acted upon it.
The pair married after Corbett hired Martens as an au pair for the children following the death of his first wife in 2006. Corbett and Martens became romantically involved and moved to North Carolina where Corbett worked for a pharmaceutical company.
The Irish Independent report 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 was also reported that Corbett denied Martens her request to adopt the children after she showed a desire for a stepparent adoption.
When charged with the murder, Martens and her father were told to hand over their passports and ordered not to have any contact with the children.