"Evidently if they suspect her they have concluded that Mrs. Langmore
was killed first."

"That is their idea, but it looks to me as if both were killed at about
the same time, although I know that couldn't very well be."

"No, not if one was upstairs and the other down. Do you think it
possible that one killed the other and then committed suicide?"

At this Raymond Case started back.

"I had not thought of that!" he cried. "If it is true then that clears
Margaret." Evidently he was thinking only of the girl he
loved--everything else concerning the mystery was of secondary
consideration.

"Such a thing is possible, although not probable, unless the two had a
bitter quarrel between themselves. Every crime must have a motive.
People do not commit murder unless there is a reason for it or unless
they are insane. Motives may be divided into three classes--jealousy,
revenge, or gain. In this instance I think we can throw out
jealousy--"

"Mrs. Langmore was jealous of Margaret."

"And wasn't the young lady jealous of her stepmother in a way?"

"But she is not guilty--I'll stake my life on her innocence."

"Then let us come down to revenge or gain. You say nothing was stolen.