Then use your brain, such as it is, to eliminate the impossible, which in this case is the ghost, and observe what remains, which in this case is a solution so blindingly obvious even Lestrade could work it out!
頭を使え 不可能を除外しろ この場合は亡霊 そして残ったものを観察しろ レストレードでさえ分かるほど - 明らかな答えだ