Without Warning! (1952)

Carl Martin is a morose and deranged Los Angeles gardener, who, in retribution for the infidelity of his unfaithful wife, sets about to kill as many blondes as he can. From the time the film opens, to the sound of a radio turned up full-blast over the still-warm corpse of a blonde, the audience knows the identity of the killer. The film depicts, with documentary realism (as it was shot on location in and around Los Angeles), how the police, using laboratory techniques against the few clues they have, track down Martin. Their key clue is a spring from a pair of garden shears. The police move in just as Martin is about to add Jane Saunders, the daughter of a greenhouse owner, to his long list of victims.