The constable is found lying on the tank, but he is not dead—he has simply fainted from fright. The perpetrator is a "writhing yellow something, like an eel or a snake... flat as a ribbon." This creature has emerged from the tank, via a pipe, and climbed up onto the railing around the tank. The doctor's belief is confirmed; we learn that when he investigated the original crime he discovered slime on the tank railings and moisture on the collars of the victims. The exact nature of the creature remains a mystery, as its head has been destroyed by the shotgun blast, but the doctor believes that it is an abnormal creature because it developed under "abnormal conditions."