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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.

Before Riehl opened fire on Douglas County deputies early Sunday morning, he was busy on Facebook calling them “clowns.”

His anger also shows up in a different YouTube video about the Lone Tree Police Department, where he repeatedly calls officers “Nazis” and “scumbags.” He also repeatedly laughs at his own comments.

Riehl’s anger apparently stemmed from a Nov. 17 traffic stop.

He acquired body camera footage of him getting pulled over, then narrates his displeasure as he plays the video on a film screen.

At one point, Riehl said into his recorder, “This is the type of serial harassment in law enforcement.”

The social media police criticisms were never overtly threatening, but other Facebook posts, which targeted several of his University of Wyoming law professors, were.

Riehl received his law degree in 2010, but records show he no longer has an active bar or attorney license.

On Facebook, his vile rants included dreaming about raping a former male professor.

That threat and possibly others posted online prompted an all-campus warning in November. Police emailed Riehl’s picture and a photo of his vehicle with the message, “Students are also asked to immediately notify UWPD if they observe the former student or his red Ford Foxbody Mustang with Colorado plates.”

“No matter the problems that he was in, upon reflection he always felt sorry for himself. It wasn’t his fault. Something was always done to him,” former law school classmate Ember Oakley said.

She said he always played the “poor me” card and was a “manipulative” person.

“He seemed to instigate problems and malign people and smirk, be underhanded. And when he was called out on his behavior he normally wouldn’t stop, but more importantly, he always found himself to be the victim,” Oakley said.

Oakley said she never saw any signs of mental illness.

“He didn’t seem to have that deranged obsession nine years ago when we were in school,” she said.

Riehl’s social media pages also include photos of him shooting a shotgun and an AR-15-style rifle last summer.

The pictures trace back to Kenaz Tactical Group and a defensive firearms course in Colorado Springs.

“This summer Mr. Riehl attended defensive firearms courses which were conducted in Colorado Springs, CO by our company,” Kenaz Tactical Group said in a statement.

“Mr. Riehl’s demeanor during the training sessions was not alarming, he interacted well with other students and seemed proud of his military career. Mr. Riehl provided his own firearms during the training sessions.

“We are prepared to cooperate fully with any law enforcement investigation that may result.”