Matthew Riehl, the man who shot seven people on Sunday in suburban Denver and killed a sheriff's deputy while livestreaming the ambush, last fall sparked a security crackdown on the campus of the University of Wyoming College of Law.

Riehl, 37, graduated from the law school in 2010, but came on the radar of administrators in late October after posting threatening messages on Facebook criticizing some former professors. In one post, according to a report from a Colorado news station, Riehl wrote about a dream of raping a male professor. A university spokesman said Riehl's posts did not include specific threats. Other posts focused on what Riehl viewed as serial harassment by police in Colorado, where he lived at the time of the shooting. He was shot and killed by police.

The Laramie, Wyoming, law school responded to Riehl's Facebook by warning students to be on the lookout for Riehl and his vehicle. A Nov. 6 email to students from assistant dean Lindsay Hoyt described Riehl as a suspicious person.

“The UW Law School has received information about suspicious behavior involving a former student,” reads the email, which was obtained by a Wyoming radio station. “There have been no direct threats to faculty, staff, or students, but as a precaution, students are being notified of this situation.”

The email instructed students to notify campus police if they saw Riehl or his red Ford Mustang on or near campus. It included Riehl's photo and a picture of his vehicle.

Hoyt and law dean Klint Alexander did not immediately respond to requests for comment Tuesday, though university spokesman Chad Baldwin confirmed in an interview Tuesday that campus police had been investigating his social media posts that mentioned the school. They increased security on campus for several days and campus police warned Colorado law enforcement about him.

According to police in Colorado, in the early hours of Dec. 31, Riehl lured police to his Douglas County apartment under the guise of a domestic disturbance. He opened fire on the responding officers, killing 29-year-old Douglas County Deputy Zackari Parrish. He wounded four other officers and two civilians, and fired more than 100 rounds.

Riehl landed on the law school's honor roll in 2007, Baldwin said, but faculty flagged him as a troubled student while he was on campus. Riehl was the subject of a harassment investigation as a student, although campus police never found enough evidence to take action against him, Baldwin said. He did not know whether the alleged harassment was directed at a fellow student or faculty member.

The harassment investigation may have stemmed from an incident in which Riehl took offense to a comment a student who was serving as a moot court judge directed at him, said Charles Pelkey, a state lawmaker and attorney who attended law school with the shooter and kept in touch via Facebook. Pelkey said in an interview Tuesday that Riehl left a women's douche in the study carrel of his perceived enemy, and that the incident generated much discussion on campus.

“He was kind of an odd character and a relatively quiet guy,” Pelkey said. “He had a relatively juvenile sense of humor. He could be snarky.”

More recently, Riehl's behavior ventured into delusional and paranoid, Pelkey added. He blocked Riehl on Facebook this summer after Riehl lashed out over a post Pelkey authored condemning President Trump's attacks on transgendered servicemembers. “Matt went off on me,” Pelkey recalled. “It was a lot of really bizarre stuff. It got insulting and vitriolic.”

The social media posts regarding the law school came to administrators' attention in October were, “really vulgar and awful, and just fairly alarming in terms of his mental health,” Baldwin said. “It showed a guy who was unhinged and who had a lot of rage.”

The posts were directed at individual faculty members, Baldwin added.

Riehl formerly worked as an attorney in Rawlins, Wyoming, a small town outside of Laramie, but did not appear to be a current member of the bar. Pelkey said he let his bar membership there lapse. Riehl joined the U.S. Army Reserve in 2003 and was deployed to Iraq in 2009. He was honorably discharged in 2012.

Wyoming attorney Ember Oakley, who graduated with Riehl from the law school in 2010, told a Colorado television station that he did not appear to be mentally ill while in law school. Yet he displayed something of a persecution complex and was manipulative, Oakley said.

“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,” Oakley said. “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.”

Riehl's LinkedIn profile  describes him as a solo practitioner in Rawlins beginning in 2014 and does not list any other employment. Riehl does not appear in databases of licensed attorneys in either Wyoming or Colorado.