SYRACUSE, N.Y. (AP) — A former high school track coach faces at least 15 years in prison after admitting he persuaded a young teenager to produce sexually explicit images of another child under 14.

The U.S. Attorney's Office in Syracuse says 32-year-old Martin Nicholson of Geddes pleaded guilty in federal court Thursday to a child sexual exploitation charge.

Nicholson admitted he threatened to cut off a relationship he was having with a minor unless the requested sexual images were produced. He also admitted he sent the images to other users online.

Investigators caught Nicholson trading child pornography over Twitter.

He faces a mandatory minimum sentence of 15 years and a maximum of 30 years in prison when he's sentenced in February.