`Hadley,' he said, `that's an omen. It's coincidence carried to the nth degree. I couldn't have believed it, and I'm glad we didn't hear it at the beginning of the investigation; it would only have confused us.'
`What are you talking about?'
`Let's hear the full outline of what Bitton did, as you read it.,
Hadley settled back with a chicken sandwich.
`Well it's fairly plain. Bitton had made up his mind to kill Driscoll when he returned from the trip. He was a little mad, anyhow, if his behaviour tells everything, and it explains what happened afterwards.
`I don't think he intended at first to make any secret of it. His plan was simply to go to Driscoll's flat and choke the life out of him; and he made up his mind to do it that morning. He was determined to see Driscoll, you know. He borrowed Sir William's key to be sure he could get into the apartment.
`He arrived there, and Driscoll was out. So he prowled through the apartment. In all likelihood he was looking for incriminating evidence against his wife and her lover. You remember the oil and the whetstone on Driscoll's desk? The oil was fresh; Driscoll had probably been working on that crossbow bolt, and it was lying there conspicuously. Remember that the bolt had a significance to Bitton; it was one which he and his wife had bought together….'
Dr Fell rubbed his forehead. `I hadn't thought of that,' he muttered; `the omens are still at work. Carry on, Hadley'
`And he found the top-hat. He must have surmised that Driscoll- was the Mad Hatter, but that didn't interest him so much as a recollection of Driscoll's wish to die in a tophat. You see the psychology, Fell? If he'd merely run across a top-hat of Driscoll's, the suggestion mightn't have been so strong. But a hat belonging to his brother — a perfect piece of stage-setting…’
`Suddenly, his plan came to him. There was no reason why he should suffer for killing Driscoll. If he stabbed Driscoll at some place which wouldn't be associated with Lester Bitton, and put the stolen hat on the body, he would have done two things: First, he would have put suspicion on the Mad Hatter as the murderer. But the hat-thief was the man he was going to kill!… and consequently, the police could never hang an innocent person for murder.