SIOUX FALLS, S.D. (KELO) -- A former Sioux Falls middle school teacher faces 20 new child porn charges. According to documents filed in federal court, the alleged crimes had been happening significantly longer than investigators originally thought. We first told you about Justin Preuschl in March, when he was charged with solicitation of a minor and lost his teaching job. Former SF teacher faces more child porn charges The case eventually moved to federal court, where Preuschl was initially accused of committing 16 crimes between June of 2023 and January of this year. He's now charged with 36 counts, beginning in December of 2022. The US Attorney's office says he posed as a 15-year-old boy online and pressured multiple girls to send him sexually explicit materials. He also attempted to send them pornography. Preuschl was employed at Whittier Middle School at the time of some of the alleged crimes.