Saw the same comment; rather curious, particularly when the police in the community where he lived (Mesquite) had no reported contact with him.
And even that is a little odd; the shooter was (reportedly) the manager of a retirement complex. Folks who run apartment or condo complexes have frequent contact with the cops, who investigate crimes on the property, handle evictions, serve warrants, etc. Admittedly, a senior complex is usually fairly quiet (and the cops don’t show up as often), but the notion of him being an “unknown” to local police is a bit odd.
I’m guessing “known to police” means he had been making threats of some kind. I can’t believe anyone would have a 13 tattoo when they had never been to prison.