FLINT, Mich. (CBS LOCAL) — A Michigan girl’s nightmare is finally over after a man was arrested for sexually assaulting the juvenile and threatened her life in what the sheriff is calling a “sadistic torture relationship.”

According to police, 22-year-old Derek Sewell began abusing the girl as a 13-year-old after she ran away from home three years ago. Sewell reportedly lived in the home of the girl’s parents prior to her running away. Genesse County Sheriff Robert Pickell revealed to reporters the horrific nature of the charges against Sewell.

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“This is the guy that inflicted torture and imprisonment on a young 13-, 14-, 15-year-old child,” said Pickell. “We don’t know as of this time that he ever human trafficked her, but the relationship was one of a sadistic nature.”

Sewell allegedly abused the girl every day and according to Sheriff Pickell, he cut her feet and thighs with a knife. He also allegedly threatened to kill the girl on multiple occasions and even held her head and neck under water. The girl escaped and ran back to her parents’ house two weeks ago.

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“She said she was always in fear of her life,” said Sheriff Pickell.

Sewell was arrested on eight criminal charges, and five of them carry the maximum of life in prison.