OKLAHOMA CITY — A man charged with killing his father, who was Oklahoma’s labor commissioner, repeatedly stabbed him with a large kitchen knife in the neck and head at a busy restaurant while his mother tried to stop him, police said Monday.
Christian Costello, 26, was being held on a preliminary first-degree murder charge Monday after the Sunday night killing of his father, Mark Costello. The son had asked his parents to meet him at the Braum’s fast-food restaurant in Oklahoma City, where he argued with his father while his mother waited outside.
‘‘What set him off to attack the commissioner, we still don’t know,’’ Oklahoma City police Captain Paco Balderrama said at a news conference.
Family members issued a statement through a spokesman on Monday saying they couldn’t adequately express the ‘‘shock and sadness’’ they were feeling. They also mentioned that Christian Costello has a mental illness, although they didn’t add any details.
In a plea bargain over a DUI charge, Christian Costello said he was once confined for three months so that he could be treated for mental illness, according to court records.
His father was considered a rising star in Republican Party politics. Mark Costello took 64 percent of the vote against an incumbent Democrat in 2010, and the telephone software company founder was reelected last year.
Sunday evening, officers were called to the ice cream and fast-food restaurant after a stabbing was reported. Mark Costello, 59, died at a hospital.
Governor Mary Fallin directed that flags be lowered to half-staff for the rest of the week.
State law requires her to appoint a successor to complete the remainder of Costello’s term, which ends in 2018.