Israel Zangwill

To commit a crime that is invisible, one must engineer the very impossibility of discovery.

She cowered back, for an instant (I divined rather than saw the action) she shut off the dreaded sight with her hands. In that instant I had made my cut—precisely, scientifically—made so deep a cut and drew out the weapon so sharply that there was scarce a drop of blood on it; then there came from the throat a jet of blood which Mrs. Drabdump, conscious only of the horrid gash, saw but vaguely. I covered up the face quickly with a handkerchief to hide any convulsive distortion. But as the medical evidence (in this detail accurate) testified, death was instantaneous. I pocketed the razor and the empty sulfonal phial. With a woman like Mrs. Drabdump to watch me, I could do anything I pleased. I got her to draw my attention to the fact that both the windows were fastened.