HELENA, Mont. — A North Carolina man who pleaded guilty to coercing two Montana girls into sending him nude photographs of themselves has been sentenced to 15 years in prison.

The U.S. Attorney's Office in Montana says 54-year-old Theodore J. Castine of Mooresville, N.C., was sentenced Thursday by U.S. District Judge Charles Lovell in Helena. Castine earlier pleaded guilty to two counts of sexual exploitation of children.

Prosecutors said Castine contacted a 14-year-old Helena girl via Facebook and text messages demanding that she send him pictures or that he would find her. The girl sent the pictures and contacted authorities, who took over the girl's accounts, identified Castine and arrested him.

Authorities found pictures of another Helena girl in Castine's email account. Prosecutors say Castine coerced her in a similar fashion.