The man was making a hurried telephone call when the murderer entered.

Consequently, we are driven to the inevitable alternative that the murderer entered by the front door.

Willington's lips wore a smile as the murderer entered a cab.

The real murderer must have entered and left by a secret exit in the cellar.

The murderer could not have entered the house after 6:30 pm, since at that time the drawbridge was up.

The only curious thing is, though, that I think the murderer did actually enter by the window.

Very obviously," declared Cardona, "the murderer entered by this window.

The murderer entered the office while the door was unlocked.

This key, however" - Cardona pointed to the floor - "gives us an answer to how the murderer entered.

The film ends just as Humpty's apparent murderer enters the room (though they are not shown).