Death of a Viewer by Herbert Adams — Read

There was a long silence. The old man who had suffered such terrible shocks in so short a time still sat in his chair, his eyes closed and, his face, mask-like, void of expression. The admission as to the gun completed the case as far as Roger was concerned. He had no more to say on that issue and was grieved rather than exultant at the accuracy of his deductions. He waited for Bethesda to speak. At last came the poignant question--"As you have discovered so much, Major Bennion, I suppose you are also convinced as to who killed my wife?"

-"I am most regrettably forced to a certain conclusion," Roger replied. "An inevitable sequel."