When on the top of this I am able to show that the blood mark on the windowsill was deliberately placed there by Barker, in order to give a false clue to the police, you will admit that the case grows dark against him.
"Now we have to ask ourselves at what hour the murder actually did occur.

Up to half-past ten the servants were moving about the house; so it was certainly not before that time.

At a quarter to eleven they had all gone to their rooms with the exception of Ames, who was in the pantry.

I have been trying some experiments after you left us this afternoon, and I find that no noise which MacDonald can make in the study can penetrate to me in the pantry when the doors are all shut.
"It is otherwise, however, from the housekeeper's room.

It is not so far down the corridor, and from it I could vaguely hear a voice when it was very loudly raised.