"Might just have come out of the shop," grunted Colwall. "Looks like new, barring a few scratches. Well, none of my men destroyed any prints, that I will answer for!"
"I don't suppose they did. This case has been carefully polished."
"Well, that has torn it!" Colwall said. "Do you figure it was planted in the room to throw suspicion on young Herriard?"
"That's about the size of it," said Hemingway. "One thing's certain: he didn't leave it there himself."
"Then it pretty well clears him," said. Colwall regretfully. "I must say, I thought all along it was him. A bit disheartening, isn't it?"
"I wouldn't say that," replied Hemingway, who seemed to have recovered his cheerfulness. "In fact, I regard it as a highly promising development."
"I don't see how you make that out," said Colwall, staring at him.
"I was beginning to think that this was going to be the one case where the guilty party didn't once slip up. Well, he did slip up," said Hemingway, pointing an accusing finger at the cigarette-case. Just like a lot of others before him, trying to be too clever. The way I see it, planting this case was an unrehearsed effect. If he'd thought of it when he worked out the rest of his details, I daresay he'd have arranged for us to have found Stephen's finger-prints on the case. We can take it that Miss Dean's testimony was correct: she put the case down on the table at her elbow. Our unknown friend saw it there, and thought it would make a nice piece of evidence against Stephen. He picked it up, and probably slipped it into his pocket, either forgetting not to touch it with his bare hand, or not having the time to handle it through his handkerchief. But when it came to planting it, he wasn't the man to forget that he mustn't leave any prints on it, so he polished it good and hard. Well, it's restored my belief in the fundamental stupidity of murderers. They all slip up sooner or later, though I admit this one's sharper than most."
"That's all very well, but I don't see how it's going to help you."
"You never know," said Hemingway, lifting the cigarette-case out of the crutch, and regarding it with a loving eye.