By Pat Loeb

PHILADELPHIA (CBS) – The son of a man who opened fire and killed two women in a Delaware courthouse, Monday, will be in federal court for a detention hearing this morning. He’s been charged with a probation violation but he’s also the ex-husband of one of the victims and suspected of involvement in her murder.

The charges against David Matusiewicz are prosaic — suspected of being in Maryland when he said he was in New Jersey — but authorities are investigating his role in the murder of his ex-wife Christine Belford and her friend Laura Mulford, shot by his father Thomas Matusiewicz when they arrived at the New Castle County Courthouse for a child support hearing, as part of a long-running custody dispute.

Matusiewicz was on probation after kidnapping the children and was at the courthouse when his father opened fire. His father killed himself after also firing at police. The Matusiewicz family lives in Texas and authorities say they’re working with police there, who’ve searched the family home, identifying David, his mother and his sister all as suspects in the shooting.