Rumor has it that STEM school took in kids who'd been kicked out of other schools. Which is not how things are done in Colorado.
No sauce because this info was emailed to my roomie by a Coloradan. Sounds bogus even to me but it would explain https://www.dailymail.co.uk/news/article-7012485/Father-Colorado-school-shooter-Alec-McKinney-serial-felon-illegal-immigrant.html