"I'll tell you what you did that night," answered Kirby, without the least trace of doubt in voice or manner. "When Mrs. Hull pulled down the blind, you ran up to the roof an' cut down the clothes-line. You went back to the fire escape, fixed up some kind of a lariat, an' flung the loop over an abutment stickin' from the wall of the Paradox. You swung across to the fire escape of the Paradox. There you could see into the room where Cunningham was tied to the chair."
"The blind doesn't fit close to the woodwork of the window. Lookin' in from the right, you can see the left half of the room. If you look in from the other side, you see the other part of it. That's just what you did."
For the moment Olson was struck dumb. How could this man know exactly what he had done unless some one had seen him?
"You know so much I reckon I'll let you tell the rest," the Scandinavian said with uneasy sarcasm.
"Afraid you'll have to talk, Olson. Either to me or to the Chief at headquarters. You've become a live suspect. Figure it out yourself. You threaten Cunningham by mail. You make threats before people orally. You come to Denver an' take a room in the next house to where he lives. On the night he's killed, by your own admission, you stand on the platform a few feet away an' raise no alarm while you see him slugged. Later, you hear the shot that kills him an' still you don't call the officers. Yet you're so interested in the crime that you run upstairs, cut down the clothes-line, an' at some danger swing over to the Paradox. The question the police will want to know is whether the man who does this an' then keeps it secret may not have the best reason in the world for not wanting it known."
"What you mean--the best reason in the world?"
"They'll ask what's to have prevented you from openin' the window an' steppin' in while my uncle was tied up, from shootin' him an' slippin' down the fire escape, an' from walkin' back upstairs to your own room at the Wyndham."
"Are you claimin' that I killed him?" Olson wanted to know.
"I'm tellin' you that the police will surely raise the question."
"If they do I'll tell 'em who did," the rancher blurted out wildly.
"I'd tell 'em first, it I were in your place. It'll have a lot more weight than if you keep still until your back's against the wall."