Copycat?
One way for the copycatting to be reduced is to stop using the perp’s name in the various stories. Don’t give them the infamy they oftentimes desire. Maybe use their initials and age or maybe just give them a number. “Perp #2863 did (insert crime list here) and was killed by local armed citizens before the police arrived on the scene” or whatever the case may be.
Once these freaks realize that their name isn’t going to be part of the sordid history of this country’s most notorious, they might think twice about committing these heinous acts. If even one copycat doesn’t go through with it, it’ll have been worth it.