A father came home to find his 43-year-old girlfriend naked from the waist down as she fled from his 13-year-old son's bedroom.
Pamela Ann Fahy has been charged with sex abuse after she was arrested in Winona County, Minnesota.
The teen's father called authorities after he came home early Sunday and found his middle-aged girlfriend running from the boy's bedroom without any knickers.
When pressed, the boy told his father that he and Fahy had been having sex for several months.
The boy's father found Fahy's underwear on the floor next to his son's bed.
According to the local paper, investigators soon learned that the sexual encounters had taken place in a number of locations, including Fahy's mobile home.
She told detective she had had both intercourse and oral sex with the boy in multiple places all over Winona and Wabasha counties.
If found guilty, Fahy could face 15 years in prison.