The Problem of the Perfect Alibi

Next morning at eight o'clock, Paul Randolph De Forrest, a young man of some social prominence, was found murdered in the sitting room of his suite in the big Avon apartment house. He had been dead for several hours. He sat beside his desk, and death left him sprawled upon it face downward. The weapon was one of several curious daggers which had been used ornamentally on the walls of his apartments. The blade missed the heart only a quarter of an inch or so; death must have come within a couple of minutes.