In White Raiment by William le Queux

My eyes wandered from the face of the trembling woman before me to the blanched countenance of my love. In an instant I detected a change there. While I had been speaking the muscles had relaxed until that face I adored had become blank and quite expressionless. No deep medical knowledge was necessary to detect the awful truth. It was the exact counterpart of the photograph which had been in the Colonel's possession.

With a cry of despair I sank upon my knees, touching her cheeks and chafing her hands. I held the mirror against her mouth. But the jaw had dropped, and when I looked eagerly for signs of respiration, there were none. Beryl, my mysterious, unknown wife, was dead.