Shooter threatened law professors, police before killing
HIGHLANDS RANCH, Colo. -- Douglas County shooter Matt Riehl had no criminal background, but according to the sheriff's office, he was "known to them." Part of that reason was Riehl’s angry, strange and threatening social media postings. Riehl used the alias “Matt Gonzo” on Facebook. Using various means of video recording, Riehl complained about the politics and tactics of several local police agencies.