BOSTON (CBS) – A former Newton elementary school teacher accused of sexually assaulting children and trading child pornography online has been sentenced to 45 years in prison.

Last August, David Ettlinger pleaded guilty to engaging in a child exploitation enterprise. Evidence showed that he had been an active member of Dreamboard, an online child pornography bulletin board, since 2009.

Ettlinger also took secret photos of students at Underwood Elementary School in Newton, where he was a second grade teacher.

In addition to his prison term, Ettlinger was sentenced to lifetime supervised release.