That is what I realized just as Miss Johnson realized it.
Her window was directly underneath, on the side away from the courtyard.
And Dr Leidner was alone up there with no one to witness his actions.
And those heavy stone querns and grinders were up there all ready to his hand.
So simple, so very simple, granted one thing that the murderer had the opportunity to move the body before anyone else saw itOh, it is beautiful of an unbelievable simplicity!
Listen it went like this:
Dr Leidner is on the roof working with the pottery.
He calls you up, Mr Emmott, and while he holds you in talk he notices that, as usually happens, the small boy takes advantage of your absence to leave his work and go outside the courtyard.
He keeps you with him ten minutes, then he lets you go and as soon as you are down below shouting to the boy he sets his plan in operation.
He takes from his pocket the plasticine-smeared mask with which he has already scared his wife on a former occasion and dangles it over the edge of the parapet till it taps on his wifes window.
That, remember, is the window giving on the countryside facing the opposite direction to the courtyard.
Mrs Leidner is lying on her bed half asleep.
She is peaceful and happy.
Suddenly the mask begins tapping on the window and attracts her attention.
But it is not dusk now it is broad daylight there is nothing terrifying about it.
She recognizes it for what it is a crude form of trickery!
She is not frightened but indignant.
She does what any other woman would do in her place.
Jumps off the bed, opens the window, passes her head through the bars and turns her face upward to see who is playing the trick on her.
Dr Leidner is waiting.
He has in his hands, poised and ready, a heavy quern.
At the psychological moment he drops it
With a faint cry (heard by Miss Johnson) Mrs Leidner collapses on the rug underneath the window.
Now there is a hole in this quern, and through that Dr Leidner had previously passed a cord.
He has now only to haul in the cord and bring up the quern.
He replaces the latter neatly, bloodstained side down, amongst the other objects of that kind on the roof.
Then he continues his work for an hour or more till he judges the moment has come for the second act.
He descends the stairs, speaks to Mr Emmott and Nurse Leatheran, crosses the courtyard and enters his wifes room.
This is the explanation he himself gives of his movements there:
I saw my wifes body in a heap by the bed.
For a moment or two I felt paralysed as though I couldnt move.
Then at last I went and knelt down by her and lifted up her head.
I saw she was deadAt last I got up.
I felt dazed and as though I were drunk.
I managed to get to the door and call out.
A perfectly possible account of the actions of a grief-dazed man.
Now listen to what I believe to be the truth.
Dr Leidner enters the room, hurries to the window, and, having pulled on a pair of gloves, closes and fastens it, then picks up his wifes body and transports it to a position between the bed and the door.
Then he notices a slight stain on the window-side rug.
He cannot change it with the other rug, they are a different size, but he does the next best thing. He puts the stained rug in front of the washstand and the rug from the washstand under the window.
If the stain is noticed, it will be connected with the washstand not with the window a very important point.
There must be no suggestion that the window played any part in the business.
Then he comes to the door and acts the part of the overcome husband, and that, I imagine, is not difficult.
For he did love his wife.
My good man, cried Dr Reilly impatiently, if he loved her, why did he kill her?
Wheres the motive?
Cant you speak, Leidner?
Tell him hes mad.
Dr Leidner neither spoke nor moved.
Poirot said: Did I not tell you all along that this was a crime passionnel?