‘No fingerprints,’ he announced. ‘But just look at that key, sir. Take a look at it with that magnifying glass there.’
Poirot bent forward. He and Johnson examined the key together. The chief constable uttered an exclamation.
‘By Jove, I get you. Those faint scratches on the end of the barrel. You see ’em, Poirot?’
‘But yes, I see. That means, does it not, that the key was turned from outside the door—turned by means of a special implement that went through the keyhole and gripped the barrel—possibily an ordinary pair of pliers would do it.’
The superintendent nodded.
‘It can be done all right.’
Poirot said: ‘The idea being, then, that the death would be thought to be suicide, since the door was locked and no one was in the room?’
‘That was the idea, M. Poirot, not a doubt of it, I should say.’
Poirot shook his head doubtfully.
‘But the disorder in the room! As you say, that by itself wiped out the idea of suicide. Surely the murderer would first of all have set the room to rights.’
Superintendent Sugden said: ‘But he hadn’t time, Mr Poirot. That’s the whole point. He hadn’t time. Let’s say he counted on catching the old gentleman unawares. Well, that didn’t come off. There was a struggle—a struggle heard plainly in the room underneath; and, what’s more, the old gentleman called out for help. Everyone came rushing up. The murderer’s only got time to nip out of the room and turn the key from the outside.’
‘That is true,’ Poirot admitted. ‘Your murderer, he may have made the bungle. But why, oh why, did he not at least leave the weapon? For naturally, if there is no weapon, it cannot be suicide! That was an error most grave.’
Superintendent Sugden said stolidly:
‘Criminals usually make mistakes. That’s our experience.’
Poirot gave a light sigh. He murmured:
‘But all the same, in spite of his mistakes, he has escaped this criminal.’
‘I don’t think he has exactly escaped.’
‘You mean he is in the house still?’
‘I don’t see where else he can be. It was an inside job.’
‘But, tout de même,’ Poirot pointed out gently, ‘he has escaped to this extent: You do not know who he is.’
Superintendent Sugden said gently bur firmly:
‘I rather fancy that we soon shall. We haven’t done any questioning of the household yet.’
Colonel Johnson cut in:
‘Look here, Sugden, one thing strikes me. Whoever turned that key from the outside must have had some knowledge of the job. That’s to say, he probably has had criminal experience. These sort of tools aren’t easy to manage.’
‘You mean it was a professional job, sir?’
‘That’s what I mean.’
‘It does seem like it,’ the other admitted. ‘Following that up, it looks as though there were a professional thief among the servants. That would explain the diamonds being taken and the murder would follow on logically from that.’
‘Well, anything wrong with that theory?’
‘It’s what I thought myself to begin with. But it’s difficult. There are eight servants in the house; six of them are women, and of those six, five have been here for four years and more. Then there’s the butler and the footman. The butler has been here for close on forty years—bit of a record that, I should say. The footman’s local, son of the gardener, and brought up here. Don’t see very well how he can be a professional. The only other person is Mr Lee’s valet attendant. He’s comparatively new, but he was out of the house—still is—went out just before eight o’clock.’
Colonel Johnson said: