Thomas Matusiewicz took his own life Monday in the New Castle County Courthouse in Wilmington after ambushing Christine Belford, his son's ex-wife. A hearing was scheduled on David Matusiewicz's failure to pay child support.
A search warrant affidavit for Matusiewicz's home in Hidalgo County in the Rio Grande Valley in Texas shows authorities were looking for evidence David and Lenore Matusiewicz knew of Thomas's plans, The (Wilmington) News Journal reported.
The affidavit also revealed new details about the shooting. It said Matusiewicz hugged his son before David passed through the courthouse security checkpoint.
Police found two handwritten "death certificates" after Matusiewicz's suicide, one for Belford and another for her attorney, Timothy Hitchings.
David Matusiewicz kidnapped his three daughters in 2007. He was found in Nicaragua with the girls and his mother and pleaded guilty to the abduction and to forging Belford's signature to a document to obtain a loan before his departure.
Lenore Matusiewicz, in an interview with WPVI-TV in Philadelphia, said she and David had no knowledge of her husband's plans. She and her son served prison terms for the kidnappings.
"I wish I had known, maybe I could have done something to stop it," she said.
Amy Gonzalez, Matusiewicz's daughter, said her father had a brain tumor.
"I know he was trying to do what was best for the family. Unfortunately, it wasn't the right way," she told the News Journal.
Laura "Beth" Mulford was also killed. Two court officers who responded to the gunfire were wounded.
David Matusiewicz is now in federal custody on a charge of probation violation. A detention hearing is set for Friday in Wilmington.
Authorities have not released any information on who is caring for Belford's daughters.