A DeKalb County man was sentenced to three life sentences, plus 10 years Friday for molesting teen boys while working at Miller Preparatory Academy.

Casey Thomas, 37, was guilty of 17 of the 18 counts, including aggravated child molestation, cruelty to children and contributing to the delinquency of a minor, the DeKalb County District Attorney’s Office said.

Thomas was found guilty of molesting a number of young boys while serving as a mentor to troubled youth. Although he did not have a college degree or any formal certifications, Thomas worked as a teacher at Miller Preparatory Academy, where he met his victims.

“He is a predator and rightfully deserves to spend the rest of his life behind bars,” DA Robert James said in an emailed statement. “This sentence sends a loud message that child molestation will not be tolerated in DeKalb County. Hopefully, this sentence will begin the healing process for the victims and their family members.”

The incidents occurred from December 2010 to April 2011 while Thomas was teaching at Millers Prep, the district attorney's office previously said. He was arrested in July 2011.