The Lady from Nowhere by Fergus Hume

Shaking in the body and white in the face, Ferris looked upon the jewellery, which seemed positive evidence of his father's guilt, then flung himself back on the couch with a groan, his hand over his eyes to shut out the terrible sight -- for terrible it was to him, the son of Marmaduke Dean. Edith also gazed fearfully upon the heap of gold and glittering stones, not doubting the truth of Gebb's story.

"Yes! " said the detective, raking the jewels together and replacing them in the bag. "In looking for Miss Gilmar's confession I found these in the room of Dean. They were hidden on the top of a tall press in a dark corner, and I felt, rather than saw them. The case against your father is clear enough, Mr. Ferris, although I was doubtful of it at first. Mrs. Grix can prove that he spent the night of the twenty-fourth of July away from the Hall. The ticket I found in Miss Gilmar's room shows that he must have been there, since no one but he could have possessed, in this especial instance, a ticket from Norminster to London. I'll have the evidence of the station-master and the ticket-clerk to prove his purchase of it shortly, and finally the possession of this jewellery places the matter beyond all doubt."