A former taekwondo instructor who taught in Aurora and Douglas County will spend the next half-century in prison. Erik Chen, 32, pleaded guilty to three counts of sexual exploitation of a child. Police arrested Chen in July of last year after children said they saw him recording them in restrooms and changing rooms in rec centers in Castle Rock and Lone Tree. Police say a search of his home turned up hundreds of thousands of images of child porn. Chen ran summer camps at Han Lee’s Taekwondo Academy in Aurora and Lone Tree. Chen must also register as a sex offender.