“May not Walter Brooklyn have come in through the stable yard before it was closed, and been in the house some time before the murders? He may have been going away when your taxi-man saw him at about 11.30.”
“Even so, that doesn’t explain how he let himself out and bolted the place after him from the inside. And, in any case, George Brooklyn was still alive at 11.30, when he was seen leaving the building by the front door. He had to get back, and Prinsep, if he killed him, must have been alive too until well after 11.30.”
“And you can add to that the difficulty that George Brooklyn seems to have got back into the garden after 11.30, and that, where one man could enter unseen, so could two.”
The inspector scratched his chin. “The whole thing is a puzzle,” he said. “But there’s one thing I’m sure of. It’s a much worse puzzle if you don’t assume that Walter Brooklyn was the murderer.”
“Still, there’s nothing so dangerous as to simplify your problem by assuming what you cannot conclusively prove to be true. If I were a juryman, I certainly could not vote for a conviction on the evidence we have at present.”
“But there’s no one else who could have done it.”
“Oh, yes, there is. There’s all the population of London. I grant you we have at present no reason for suspecting any one else in particular. But that may be because we don’t know enough.”
“Then what do you want me to do?”
“Hunt, for all you’re worth, for further evidence. Don’t shut your eyes to the possibility that Walter Brooklyn may not be the murderer. Hunt for evidence of any kind, as if you were starting the case afresh.”
“And, meanwhile, Walter Brooklyn remains in custody?”