I agree with the Defence lawyer, someone put that dead animal in the tin, maybe a staff member with a grudge. The machine that puts the trays under the dough seam turning machine (a machine that makes sure that the seam made by rolling the dough between two bands to give it its loaf shape is at the bottom when it falls into the tin) has a sensor that pick up anything wrong with a loaf tin, and reject them to be check by hand, if that animal was in there it would have been rejected.