The Opal Serpent by Fergus Hume — Read

As may be guessed, the murder of Aaron Norman caused a tremendous sensation. One day the name was unknown, the next and it was in the mouths of the millions. The strange circumstances of the crime, the mystery which shrouded it, the abominable cruelty of the serpent brooch having been used to seal the man's lips while he was being slowly strangled, deepened the interest immensely. Here, at last was a murder worthy of Wilkie Collins's or Gaboriau's handling; such a crime as one expected to read of in a novel, but never could hope to hear of in real life. Fact had for once poached on the domains of fiction.

But notwithstanding all the inquiries which were made, and all the vigilance of the police, and all the newspaper articles, and all the theories sent by people who knew nothing whatever of the matter, nothing tangible was discovered likely to lead to a discovery of the assassins or assassin. It was conjectured that two people at least had been concerned in the committal of the crime, as, weak physically though he was, the deceased would surely not have allowed himself to be bound by one person, however strong that person might be. In such a case there would certainly have been a scuffle, and as the daughter of the murdered man heard his cry for help -- which was what Sylvia did hear -- she would certainly have heard the noise of a rough-and-tumble struggle such as Norman would have made when fighting for his life. But that single muffled cry was all that had been heard, and then probably the brooch had been pinned on the mouth to seal it for ever.