Moreover, by this time the policeman was standing blocking the pathway to the station.

Again, the alarm was given immediately by the other servants, who rushed to the sitting-room on hearing Susan's scream, and the policeman at once searched the house.

No one was found.
"Now what are we to make of all this?
The doctor declares that Miss Loach when discovered had been dead half an hour, which corresponds with the time the door was heard to open or shut by Thomas.

So far, it would seem that the assassin had escaped then, having committed the crime and found the coast inside and outside the house clear for his flight.

But who rang the bell?
That is the question we ask.