SPRINGFIELD (AP) – A federal judge has sentenced a former southwest Missouri teacher to 28 years in prison for sexually exploiting a child to produce pornography.

Forty-year-old Charles Gastel, of Carterville, formerly taught middle-school science in Joplin. The U.S. Attorney’s office says he won’t be eligible for parole and will spend the rest of his life under supervised release after leaving prison.

Gastel pleaded guilty in December to sexually assaulting a girl over a period of about nine years, and making video recordings of some of the assaults.

The victim is now 19 and lives in Lamar. She told police last year that Gastel began the assaults when she was 10 years old.