Authorities have arrested the son of Oklahoma’s labor commissioner after the official was stabbed to death at an Oklahoma City restaurant Sunday. Mark Costello, 59, was the victim of a fatal stabbing at a Braum’s ice cream and fast-food restaurant, said State Medical Examiner’s Office spokeswoman Amy Elliott. Witnesses reportedly told police Costello and his son, 26-year-old Christian Costello, got into an argument before the attack. Christian Costello was arrested at the scene on a first-degree murder charge, authorities said. The father and son reportedly met at the restaurant to reconcile after arguing earlier in the day.