SALEM, Ore. -- A former teacher at Pratum Elementary School in Silverton has been sentenced to 20 years in prison for 14 counts of first-degree sex abuse.

kgw.com/Marion Co. Sheriff's Office

Matthew Gould as shown in a police mug shot.

Matt Gould admitted to having abused more than 19 boys over the years - staging games of naked dodge ball where he was the only adult present, having shown numerous boys how to masturbate and holding naked hot tub parties for minors.

An estimated 30 people attended the sentencing in the Marion County courtroom, including members of victims families, Silver Falls School District administrators, teachers and others.

Gould also admitted that he had known all along that his actions were wrong and made an emotional apology shortly before sentencing.

Police found an additional 17 victims through investigation, but no charges were filed in those cases because they either took place in another county or the statute of limitations had run out in their case. They estimate there could be many more.