A 30-year-old Oakdale man was arrested Wednesday on suspicion of sexually assaulting his 13-year-old stepdaughter, authorities said.
At the beginning of the summer, the girl moved from her mother and stepfather's home in Oakdale to her father's home in Great Falls, Mont.
Oakdale police officer Michael Walsh said it was there she told her father about the alleged abuse by her stepfather.
Great Falls police contacted Oakdale police, who arrested Luke Joseph Smith on Wednesday.
He was arrested on suspicion of lewd and lascivious acts with a child younger than 14, forced sexual penetration, false imprisonment and annoying or molesting a child.