Although it is believed Dylan McLeod knew most of his victims, his writings indicate a violent, right-wing personality. From CBS Denver:

McCleod formed a publishing company in the mid-2000s called Flat Black Ink. The company’s status with the state has been delinquent for several years. But McCleod published three books via the company entitled ‘Sanction’, ‘Sanction II’ and ‘Sanction III’, under the pseudonym Roman McClay. Online readers note on Amazon that the books contain rants about topics like diversity, women, globalization and fantasies about killing people.

The Daily Beast analyzed McLeod’s social media posts:

In his posts, McLeod seemed to frequently use excerpts from his work to comment on current events, such as a COVID misinformation meme on Twitter featuring Facebook creator Mark Zuckerberg and Microsoft founder Bill Gates. The meme, posted on May 1 last year, featured the billionaires “discussing” their approach to the pandemic, with Gates being thanked for mandatory vaccinations while Zuckerberg was congratulated for an “injectable nanoworm.”
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He also gleefully indicated that some people required violence to be addressed. While discussing a 2014 YouTube video titled, “Mike Tyson DESTROYS Reporter!” on Twitter, McLeod, as McClay, blasted the “passive aggressive” reporter and praised Tyson for using “Direct Aggression”—all before hinting at threats of violence for the “WEAK.”

“This is basically the plot to my stupid book,” he wrote in April 2020. “Our entire society is made up of shitty little fucks who insult badasses & get away with it because law enforcement & social norms protect the WEAK from the STRONG. I’m over it.”

“The weak better buckle up... shit is about to get real,” he wrote.

New York’s Daily News reports that McLeod “had been ‘on the radar of law enforcement’ and had been investigated in 2020 and 2021, but no charges were ever filed and Pazen did not specify the nature of the investigations.”

Here's an idea: Instead of making the police figure out which hate-filled people should be arrested, how about just preventing or limiting their danger by keeping them away from guns?