A Minnesota teacher and basketball coach who sexually abused more than 120 boys was sentenced to life in prison after a traffic stop in Idaho uncovered a vast collection of digital evidence documenting his crimes.
A new documentary, Minnesota Monster, examines how Aaron Hjermstad targeted children over more than a decade, the warning signs that were missed and the police investigation that brought his offending to light.
Hjermstad, who worked at Excell Academy in Brooklyn Park, Best Academy in Minneapolis and the youth organisation Hospitality House, was first convicted in 2021 of sexually abusing four boys. He was sentenced to 12 years in prison.
Before he was due to be sentenced, however, Hjermstad left Minnesota. Hennepin County prosecutors suspected he was attempting to avoid being taken into custody.
He was arrested in Idaho Falls after being stopped by state troopers during what began as a routine traffic check. A search of his hire car uncovered laptops, hard drives and other digital storage devices.
Police footage from the stop shows Hjermstad appearing to laugh when asked about the contents of the hard drives. At one point, he said: “My life is over.”
The material recovered from the car led investigators to evidence of abuse involving more than 100 boys. Investigators also found a list containing the initials of 127 children whom Hjermstad had recorded abusing over several years.
Janese Brown, the Minnesota Bureau of Criminal Apprehension special agent who led the investigation, described the offending as calculated and planned. The volume of material was so large that digital forensic specialists took a considerable time to process it.
How the teacher targeted boys
Prosecutors and victims said Hjermstad cultivated relationships with young boys, many of them from disadvantaged backgrounds, by presenting himself as a trusted teacher, coach and mentor.
Several victims were invited to sleepovers at his home, where he had created a child-friendly environment with video games, air hockey and a pool table. Prosecutors said those arrangements formed part of a grooming process.
The mother of one former student said her family only learned in 2024 that the boy had appeared in abuse recordings. The child, who was nine when he first met Hjermstad, has said he believes he may have been drugged.
“We were his prey,” the former student said in the documentary. He described Hjermstad’s public image as that of a white adult helping black boys, while concealing what he called “really horrible things”.
Jeff Anderson, a lawyer representing several former students, described Hjermstad as one of the most prolific offenders he had encountered in four decades of handling sexual abuse cases.
Warnings missed by schools and organisations
A 12-year-old student reported Hjermstad to authorities in 2015 while he was working at Excell Academy. Prosecutors did not bring charges at the time, saying the evidence could not establish the case beyond reasonable doubt.
Excell did not renew Hjermstad’s contract, but he retained his Minnesota teaching licence. Hospitality House, where he volunteered as a coach, temporarily suspended him before reinstating him with restrictions, including a ban on overnight stays involving children at his home.
He later secured work at the Minneapolis school then known as Mastery, which subsequently merged with Best Academy. The Minnesota Supreme Court found in February 2025 that the school could not automatically claim immunity from a negligence lawsuit over its hiring process.
The court said Best Academy had failed to show that it had properly investigated Hjermstad’s background, including by obtaining reference letters and contacting his previous employers. The ruling sent the case back to a lower court for further proceedings. ([law.justia.com](https://law.justia.com/cases/minnesota/supreme-court/2025/a22-1236.html))
A civil claim brought by a former student was later settled. Best Academy said previously that the allegations against Hjermstad were deeply disturbing, but declined to comment on pending litigation. Excell Academy and Hospitality House did not respond to requests for comment.
Life sentence after further convictions
The evidence found in Idaho led to charges relating to 12 additional boys. Hjermstad pleaded guilty in September 2025 to 12 counts of first-degree criminal sexual conduct covering offences committed between 2013 and 2020.
He was sentenced in November 2025 to life in prison, with the possibility of parole after 30 years. He must also register as a predatory offender and would remain subject to lifetime conditional release if he were ever freed. ([hennepinattorney.org](https://www.hennepinattorney.org/news/news/2025/November/hjermstad-sentencing))
Hennepin County Attorney Mary Moriarty said the sentence would prevent Hjermstad from causing further harm for decades. His conviction spared victims from having to give evidence at a trial.
The mother of one former student said the boys should be proud of the part they played in bringing the abuse to an end.
“They did what a lot of adults should have done – they literally stopped him,” she said.
