Captain Shannon by Coulson Kernahan

There was no fastening to the door of my cabin, but on passing my hand over the place where a fastening might have been expected, a flake of soft substance caught in my finger-nail and dropped to the floor. This, when I picked it up, proved to be a pellet of bread kneaded to the consistency of putty or dough. Taking the swing lamp from its bracket I examined the door more closely and saw that there had once been a fastening of some sort. A closer examination convinced me that the person who had removed the fastening had been to the pains of plugging the empty screw-holes with kneaded bread, after which he had apparently rubbed dirt-smeared fingers over the place where the fastening had been, in order to hide the marks left by removal.

When I picked out the bread-plugs -- which had only recently been put in, as they were still damp -- I saw that the screw-holes were clean inside, although there were tiny rings of dirt on the outside where the roughened edges had brushed against the fingers and collected whatever it was which had been smeared upon them.