Hannasyde looked at him. "If that is so," he said slowly, "it makes Mrs. North's evidence practically valueless."
"The second batch, you mean? It does look like it, doesn't it? Not that I ever set much store by it myself, from what you told me of her. Mind you, I don't say the murder couldn't still have happened but what I do say is that the man Glass saw - call him Charlie Carpenter - couldn't have done it. It must have been Budd, which I don't think, young Neville, North, or the dizzy blonde herself."
Hannasyde shook his head. "I can't swallow that, Hemingway. If we are to assume that Mrs. North's evidence was true, it means that Fletcher did not re-enter the study until 10.01. You yourself put the time it would take him to sit down at his desk again and start to write his letters at two minutes at the least. That leaves two minutes for the murderer to walk in, kill him, and get away again. Less, for though Glass didn't actually enter the study until 10.05, he must have had the window in view for quite a minute, on his way up the path."
"Yes, that's what he said," replied the Sergeant. "I admit it would be cutting it a bit fine. What's your idea, Chief? Think Mrs. North's first story was the true one?"
"No," said Hannasyde, after a pause. "I think she did go back into the study. If she didn't let herself out of it as she described, I don't see how her finger-prints came to be on the panel. But the fact of the hall clock's being slow points to a discrepancy somewhere in her story. She stated that the man X left the study with Ernest at 9.58, that she went back into it, and left it as the hall clock struck 10.00. Now, the only times we know to be correct are 10.02, when Glass saw X making off; and 10.05, when he discovered Fletcher's body. That left us with a difference of four minutes, between the time Mrs. North said X left and the time Glass actually saw him leave. We could just, and only just, account for that by assuming that X doubled back to the study, murdered Fletcher, and again made off. But if Fletcher returned to the study not at 10.00, but at 10.01, then there is no possibility of X's having returned, committed the murder, and reached the gate again. So either X left by the side gate at 9.58, to be followed in four minutes by a second man - Y, if you like; or the first man, X, was a pure fabrication of Mrs. North's."
"Hold on, Super! I'll have to see it on paper," said the Sergeant. He wrote for a moment or two, and regarded the result with disgust. "Yes, that is a hopeful-looking mess," he remarked. "All right - X is out. So what? We know the North dame hid in the garden, because we found her footprints. Yes, I get it. Y, who is obviously North, was with the late Ernest; she recognised his voice - or maybe she didn't: I haven't worked that bit out. Anyway, Y killed Ernest while Mrs. North was in the garden, and bunked. Mrs. North then entered the study to have a look-see, and - for reasons which I won't attempt to fathom - made off by way of the front door. You can make the times fit if you juggle with them. Someone may have passed down Maple Grove when Y reached the gate, which would mean that he'd have to wait till whoever it was had cleared off before making his getaway. Or, if you prefer it, Mrs. North didn't leave at 10.01, but later. Though why she should make that bit up, I don't quite see. That eliminates X, and fits the only facts we know to be certain."
"You can eliminate X if you like," interposed Hannasyde, "but you can't eliminate Charlie Carpenter. Where does he fit into this otherwise plausible story?"
The Sergeant sighed. "That's true. If we've got to have him in, then he's Y, and North is X - eliminated. Yes, that's all right. Mrs. North didn't recognise his voice, but she caught a glimpse of him, and thought he might be her husband. Hence her erroneous evidence. How's that?"
"Not bad," conceded Hannasyde. "But if North is eliminated, will you tell me why he stated that he spent the evening in his flat, when in actual fact he did nothing of the kind?"
"I give it up," said the Sergeant despairingly. "There isn't an answer."