A former middle school teacher in Buffalo Grove has been sentenced to 13 years in federal prison for encouraging minors to produce sexually explicit images of themselves and to then send those images and recordings to him, authorities said Tuesday.

John C. Vastis, 54, of Lakemoor, was arrested in August 2014. He is a former teacher at Meridian Middle School in Aptakisic-Tripp District 102 in Buffalo Grove.

Authorities said Vastis began communicating online with one of the victims in 2013, according to a news release. From the outset, the chats were sexually charged and for nearly a year, Vastis encouraged the victim to record sexually explicit photos and videos of himself and transmit the images over the internet to Vastis.