Well it’s sort of hard to miss a dead body literate’s with a dozen bullet holes. So underreported murders are unlikely. Rapes, maybe. Armed robbery? Possibly but not by much. Insurance requires a police report you see.
That’s the problem with the claim that crime is running amok. Petty street crime? Ok. I can see that. Minor assaults and accosted people by folks trying for chump change. Sure.
But Murders, aggravated assaults, felonious batteries. Those tend to get reported. A guy in the ER with his teeth knocked out tends to draw attention. A dead body is investigated and even the most liberal coroner will notice bullet holes.