DETROIT -- A 30-year-old Washington state man was sentenced to 55 years in prison for his involvement in a child porn ring.



Michael Berenson, of Shoreline, was sentenced Monday in federal court in Detroit. The Justice Department says he was part of a group that would manipulate underage girls into performing sexual acts on web cameras and record them without their knowledge.



Officials say he admitted to victimizing more than 1,000 girls over the span of a decade. Some of the victims were as young as 9 years old, authorities said.



Berenson was the 25th person sentenced in connection with the case. Officials say he and others involved would pose as teenage boys on social media and invite them to video chat rooms.



Berenson would also blackmail the underage girls after recording them, and also encouraged them to harm themselves, officials said. He recorded more than 1,100 hours of child pornography and his electronic devices contained thousands of other videos and images of child pornography, according to a release.



“The way that these offenders worked together to manipulate innocent girls for their own sexual gratification is truly horrific. And, the way that this defendant in particular extorted these children is especially heinous,” said United States Attorney Schneider. “Parents, please speak with your children about sextortion and cyberbullying so we can keep all of our children safe.”



In addition to his prison sentence, a federal judge ruled that he must also pay $5,000 in restitution to 16 victims identified by officials in this investigation.