The Colorado Bureau of Investigation said Monty Turner, 51, was arrested without incident about 1:30 p.m. MDT at a motel in Brandon, Manitoba, and his son, Luke Turner, was placed in protective custody until he could be reunited with his mother, The Denver Post.
Longmont police Cmdr. Jeff Satur said authorities were coordinating their efforts to get the boy home Monday and extradite his father.
Meanwhile, Satur said Missouri State Highway Patrol officers arrested the boy's grandfather, Ronald Turner, 72, in Vernon County, Mo. He was being held in the Bates County Jail in Butler on a charge of complicity to commit second-degree kidnapping.
Monty Turner is accused of breaking into his estranged wife's home in Longmont Saturday morning, and shooting her with a stun gun and pepper spray before taking his son.
The mother, Brandy Turner, has had sole custodial rights since a previous incident in which Monty Turner took Luke last July and disappeared with him until March, the newspaper said.
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