Murderer, killer, rapist, pedophile, wife beater, convict, criminal, felon, thief, liar, embezzler, con artist, forger, bum, hobo, dishonest, deceitful, traitor, unethical, petty criminal, cheat, scammer, scam artist, pick pocket, snake oil salesman, chiseler, crooked, unfaithful, drunk, addict.

And a thousand more various categories to toss people into (some refer to crimes, some refer to moral character or life situation, and some blend multiple attributes depending on context).

If a person is a rapist, you call them a rapist and not a murderer, and people know the difference. If a person is a convicted thief, you can call them a petty criminal, and nobody would confuse that with being a serial killer.