Oklahoma's Labor Commissioner Mark Costello died on Sunday after he was stabbed multiple times in the head and neck in a fast-food restaurant, cops have said.
His 26-year-old son, Christian Costello, was taken into custody in the parking lot on a first-degree murder complaint.
The duo had met at Braum's ice cream and fast-food restaurant on the northwest side of Oklahoma City so they could work out a dispute they had earlier that day, KJRH reported.
"We know they both agreed to meet, they were both there willingly, but as far as what set him off to attack the commissioner, we still don't know," Oklahoma City police Captain Paco Balderrama said on Monday.
An altercation broke out inside the restaurant before it spilled out into the parking lot, police said. Bystanders reportedly helped subdue the attacker until officers arrived.
Officers responded to the scene at 6.30pm.
They found Costello, a 59-year-old married father of five, with numerous stab wounds and rushed him to hospital, where he died, Oklahoma City Police Department Captain Paco Balderrama said. An autopsy will now be performed.
Costello's son remains in police custody. He is pictured below in a mug shot from 2014.
In a statement, Senator James Lankford said: "My family is stunned and deeply grieved to hear of the tragic death of Labor Commissioner Mark Costello.
"Mark was passionate about our nation, conservative fiscal principles, and the people of our state. Mark was a friend, and as we grieve, we will also pray for his family as they deal with this unbelievable tragedy."
My family is stunned & deeply grieved to hear of the tragic death of Labor Commissioner Mark Costello. What a tragedy.— Sen. James Lankford (@SenatorLankford) August 24, 2015
Labor Department Chief of Staff Jim Marshall said in a statement: "Our hearts ache as an agency for this tragic event and our department grieves for his family during this very difficult time."
Oklahoma Republican Party Chairman Randy Brogdon added: "I'm just numb right now, as many of us are. He was a great Christian, a good man and a wonderful husband and dad. He is going to be sorely missed."
Costello won his seat with 64 percent of the vote in 2010 and was re-elected in 2014.
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