“I suppose there is no doubt that the mark was there yesterday?”

Lestrade looks at you as if he thinks you are going out of your mind. “I don’t know whether you think that McFarlane came out of jail in the dead of the night in order to strengthen the evidence against himself,” says Lestrade. “I leave it to any expert in the world whether that is not the mark of his thumb.”

“It is unquestionably the mark of his thumb.”

“There, that’s enough,” says Lestrade. “I am a practical man, Mr. Holmes, and when I have got my evidence I come to my conclusions. If you have anything to say you will find me writing my report in the sitting-room.”

Watson turns around to you: “What do you think, Sherlock?”

“The mark wasn't there” “I don't know, if the mark was there”