The stain on the windowsill conveys the same idea. So does the card on the body, which might have been prepared in the house. That all fits into your hypothesis, Watson. But now we come on the nasty, angular, uncompromising bits which won't slip into their places. Why a cut-off shotgun of all weapons--and an American one at that?
窗台上的血迹也是出于同一目的。尸体上的卡片也是如此，卡片可能就是在屋里写好的。所有这一切都符合你的假设，华生。可是现在，我们跟着就要碰到这样一些难于处理、颇为棘手、处处对不上碴儿的问题了。为什么他们从所有武其中单单选了一支截短了的火枪，而且又是美国火枪呢？