Today's Denver Post backs up my suspicions. The perpetrator in Bailey was not legally able to own firearms.

Guess that's why he had no problem taking firearms into a "gun free" zone.

"Morrison was arrested in Aurora in 1973 for larceny and possession of marijuana, according to a CBI database. He was also charged with obstructing a police officer July 11 in Littleton for obstructing a police officer, the CBI records say. That case was pending."
http://www.denverpost.com/ci_4410326#

I do have to wonder what the "obstucting a police officer" charge is about. That sounds like a consolation prize the department takes when the perp did something else but charges weren't going to be pressed.

Yet another case of Denver-area police having someone in hand shortly before they commit a horrible crime.

From what is known today it sounds like the cops on the scene in Bailey were doing the best they could. I do not fault them. I do fault the "justice system" that lets guys like this wander off to go commit more serious crimes.