murderer vs crook

murderer and crook both are nouns.

Word	Noun	Adjective	Verb	Adverb
murderer	Yes	No	No	No
crook	Yes	No	Yes	No

As nouns, crook is a hypernym of murderer; that is, crook is a word with a broader meaning than murderer:

murderer: a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)
crook: someone who has committed a crime or has been legally convicted of a crime

Other hypernyms of murderer include criminal, felon, malefactor, outlaw, killer, slayer.

murderer (noun)	crook (noun)
a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)	a long staff with one end being hook shaped
	someone who has committed a crime or has been legally convicted of a crime
	a circular segment of a curve

murderer (verb)	crook (verb)
	bend or cause to bend