The Clock Struck One by Fergus Hume

So the long-expected had happened at last, and the inevitable woman appeared on the scene. Dora was hardly astonished to hear of Lady Burville's connection with the crime. She had always believed that, sooner or later, the name of this woman would come into the matter. Nevertheless, it was terrible that she should have killed the wretched man with whom, in some mysterious fashion, she had been associated twenty years before. With the pearl-lettered brooch in her hand, Dora considered the position in which she was placed, the discovery she had made.

"Do you think that Lady Burville really did kill him, Allen? " she asked in a hesitating voice.