Bemidji school administrators failed to protect students from an assistant principal who abused his position to solicit sexually explicit photos from underage students, according to a lawsuit filed in federal court this week.

Brandon Mark Bjerknes, 37, is serving a 25-year sentence for the sprawling scheme, which targeted more than 50 young people. Two victims and their parents — all unnamed in court documents — say Bemidji Area Schools should also be held accountable, alleging the school could have done more to stop him.

According to the lawsuit, Bjerknes used his resources at Bemidji Middle School to get information about students, then posed online as a teenager from Duluth named “Brett Larson” and persuaded them to send him graphic photos, which he shared with others. “Not only did Bjerknes use information he obtained as Assistant Principal to identify his own middle-school students to prey upon, but he also used school property to solicit, transmit, collect, and create the sexually explicit content,” according to the suit.

Bjerknes also “openly exhibited troubling behavior,” including holding closed-door meetings with female students after school and giving them candy and food as part of a “grooming technique,” the suit said. He persuaded students to charge their phones in his office during class, which is how he learned their social media handles. In September 2016, a parent complained to the school that students were being targeted online by a “Brett Larson,” but school officials ignored it, according to the complaint. If the school had acted right away, “more children could have been spared the abuse.”

Bjerknes was charged and pleaded guilty to producing and distributing child pornography and the attempted coercion and enticement of a minor in 2017. Using Facebook and Snapchat, he contacted dozens of boys and girls, some as young as 12, and engaged in sexually explicit conversations. He directed them to send him graphic photos, and sent them photos of his genitals and videos of adults having sex.

In February 2018, he was sentenced to 25 years in prison. In addition to the sentence, he will be on supervised release for life and have to register with authorities as a predatory offender.

Bjerknes worked at the school for 12 years. The lawsuit accuses the school of failing to properly investigate tips of sexual exploitation and neglecting to train staff on the threat, despite unrelated accusations in 2013 that a physical-education instructor had sexually abused students. The school has since revictimized the students by allowing their classmates to bully them, according to the suit.

The complaint alleges three counts of negligence, violations of the plaintiffs’ right to equal protection, and sexual discrimination under Title IX of the Education Amendments of 1972.

“Children have the right to a safe and healthy learning environment at school, and parents have the right to expect that schools will protect their children against sexual assault perpetrated by administrators using school devices during school hours,” said the plaintiffs’ attorney, Rebekah Bailey, in a statement. “In bringing this lawsuit, these families seek to cause real structural change in Bemidji schools so that no more children must endure what theirs have.”

Bemidji Area Schools did not immediately respond to a request for comment.

In recent years, federal law enforcement in Minnesota has struggled to keep up with the rising caseload of these types of schemes. Often called “sextortion,” the crimes involve coercion, usually on social media sites, in which a predator often poses as a teenager and manipulates a victim into sending explicit photos. In some cases, predators use these images to extort victims into giving them more images, videos or sexual favors.