The Thing on the Doorstep by H.P. Lovecraft

"The Thing on the Doorstep" is a short story written by H.P. Lovecraft, part of the Cthulhu Mythos universe of horror fiction. It was written in August 1933, and first published in the January 1937 issue of Weird Tales.
Daniel Upton, the story's narrator, begins by telling that he has killed his best friend, Edward Derby, and that he hopes his account will prove that he is not a murderer ...