According to Colorado law they didn’t need the mother to press charges.

You’re saying the cops returned the guns he used in the shooting?

Edit : Such a troubling case — dropped or not — could still have been used to trigger Colorado’s “red flag” law, which allows family members or law enforcement to ask a judge to order a removal of guns for a year from people dangerous to themselves or others, with possible extensions based on subsequent hearings.

https://www.latimes.com/world-nation/story/2022-12-06/dropped-case-foretold-colorado-bloodbath