The Latest on Oklahoma stabbing: Police say motive unknown

OKLAHOMA CITY (AP) — The latest on the fatal stabbing of Oklahoma's labor commissioner (all times local):

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9:55 a.m.

Police say the 26-year-old man accused of fatally stabbing his father, an Oklahoma politician, brought a knife to the restaurant where they'd arranged to meet.

Oklahoma City Capt. Paco Balderrama said Monday that investigators don't know yet why Christian Costello stabbed his father, Labor Commissioner Mark Costello, at the restaurant Sunday evening.

See photos of Mark Costello and the crime scene:

Balderrama says police interviewed 17 witnesses, including the victim's wife and suspect's mother, Cathy Costello, who was in a vehicle outside the restaurant.

He says he thinks Cathy Costello tried to stop her son from attacking her husband.

SEE ALSO: Police: Son arrested after Oklahoma official fatally stabbed

9:20 a.m.

Police records show that a man detained after the stabbing death of his father, Oklahoma's labor commissioner, was once held for three months for treatment of mental illness.

Records obtained by The Associated Press on Monday show that Christian Costello received a deferred sentence for driving under the influence of drugs in 2012. In his plea agreement, he disclosed the mental treatment and said he was taking mood stabilizers.

Costello is being held on a first-degree murder complaint after the stabbing death of his father, Oklahoma Labor Commissioner Mark Costello, on Sunday.

Last October, the younger Costello was accused of outraging public decency. Police say he exposed himself at a Catholic elementary school.

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