The String of Pearls (1850), p. 460

Ah, that will do, and then I defy any circumstances to find me out. How safe a—Mur—I mean a death this will be to be sure. How very—very safe."
Mrs. Oakley shook in every limb, but she kept her eyes steadfastly fixed at the small hole in the canvas, through which she could see into the room, and by a horrible species of fascination, she felt that if she had ever so much wished to do so, she could not then have withdrawn it. No ! she was as it were condemned as a fiat of destiny, as a punishment for her weak and criminal credulity regarding that man, to be a witness to. the dreadful deed he proposed committing, within the sphere of her observation.
It was dreadful. It was truly horrible. But it was not now by any means to be avoided.
Lupin disappeared for a few seconds into a room where he usually himself slept. From thence he returned with a wash-hand basin in his hand, which he placed upon the floor. He then fumbled about the clothing of his wife until he found the knife that she had twice so threateningly exhibited to him. He held it up to the light and narrowly scrutinised it.
"It will do I think," he said.
He tried its keenness upon the edge of the sole of his shoe, and he was satisfied that it had been well prepared for mischief.
"It will do well," he said. "Well, nothing can be better. From this night I shall be free from the fears that have haunted me night and day for so long. This woman is the only person in all London who really knows me, and who has it in her power to destroy all my prospects. When she is gone, I shall be perfectly easy and safe, and surely never was such a deed as this done with so much positive safety."
Mrs. Oakley felt sickened at what she saw, but still she looked upon it with that same species of horrible fascination which it is said—and said truly, too—prevents the victim of a serpents glittering eye from escaping the jaws of the destroyer. She saw it all. She did not move—she did not scream—she did not weep—but as if frozen to the spot, she, with a statuesque calmness, looked upon that most horrible scene of blood. She was the witness appointed by Heaven to see it done, and she could not escape her mission.
Lupin twined his left hand in the hair at the back of the head of the wretched woman, and then he held her head over the wash-hand basin. There was a bright flash of the knife, and then a gushing, gurgling sound, and blood poured into the basin, hot, hissing and frothing. The light fell upon the face of Lupin, and at that time so changed was it, that Mrs. Oakley could not have recognised it, and, but that she knew from the antecedants that it was no other than he, she might have doubted if some devil had not risen up through the floor to do the dead of blood.
He dropped the knife to the floor.
The murdered woman made a faint movement with her arms, and then all was over. The blood still rolled forth and filled the wash-hand basin. Lupin caught the cover from the table, throwing everything that was upon it to the floor, and wrapped it many times round the head, face, and neck of his victim.
"It is done!" he said. "It is done!"
He still held the body by the hair of the head, and dragging it along the floor, he dropped it near the door opening on to the staircase. He then went to a cupboard in the room, and finding a bottle, he plunged the neck of it into his mouth, and drank deeply. The draught was ardent spirit, but it had no more effect upon him at that moment than as though it had been so much water from a spring. That is to say, it had no intoxicating effect. It may have stilled some of the emotions of dread and horror which his own crime must have called up from the bottom even of such a heart as his. He was human, and he could not be utterly callous.
Leaning against the cupboard* door for a few seconds he gasped out—
"Yes, it is done. It is quite done, and now for the worst. Now for the body, and the vaults, and the dead. Can I do it? can I do it? I must.