"Captain Black!" exclaimed Agatha Tindale. "I called you as soon as I heard the gun go off! I think my husband has killed himself!"
Captain Black opened the bedroom door and saw Mr. Tindale lying dead under the covers. A pistol lay by the side of the bed.
"You haven't entered this room since you heard the shot?" Black asked.
"No, I was too frightened," Agatha answered. "We were all alone in the house when this happened."
Captain Black pulled the covers off the body. Mr. Tindale was dressed in pajamas. His hands were by his sides.
"A pity," said Captain Black, "for such a fine man to die."
"Yes," agreed the weeping wife.
"And a pity that I must arrest you for his murder!"
~How did Captain Black know that Agatha had killed her husband?~