Evidently she sensed Britz's lack of confidence, for she hastened to say:
"I know why he wanted to kill Mr. Whitmore. It was because Mrs. Collins was preparing to obtain a divorce in order to marry Mr. Whitmore. She had confessed her love for Mr. Whitmore and Collins had intercepted a letter from the merchant in which he urged her to obtain the divorce."
"When did Collins intercept the letter?" quickly asked Britz.
"On the morning Mr. Whitmore disappeared."
Here was something tangible at last. Not direct evidence that Collins was guilty, but circumstantial evidence of the highest importance. Not only had he threatened to kill the merchant, but he had motive for the crime, and a motive which could be established easily in a court of law.
"You say Collins will be at your house at eleven to-night?" inquired Britz.
"Yes," she answered, an eager light in her eyes. "And if you care to be there and will listen, you shall hear him confess the crime."
Her words and the tone of certainty in which she spoke almost dazed Greig. Even Britz had to struggle hard against betraying his amazement. The whole thing seemed incredible—yet the detectives had experienced more incredible happenings in the course of their long service.
"You say he will confess?" Britz said mechanically.
"More than confess," she answered. "You'll hear him gloat over the crime. He'll display his exultation before me, and I want you to be there to listen."