Kirby asked only one more question.

"You left next mornin' for Dry Valley, didn't you?"

"Yes. None o' my business if they stuck Hull for it. He was guilty as sin, anyhow. If he didn't kill the old man, it wasn't because he didn't want to. Maybe he did. The testimony at the inquest, as I read the papers, left it that maybe the blow on the head had killed Cunningham. Anyhow, I wasn't gonna mix myself in it."

Kirby said nothing. He looked out of the window of his room without seeing anything. His thoughts were focused on the problem before him.

The other man stirred uneasily. "Think I did it?" he asked.

The cattleman brought his gaze back to the Dry Valley settler. "You?

Oh, no! You didn't do it."

There was such quiet certainty in his manner that Olson drew a deep breath of relief. "By Jupiter, I'm glad to hear you say so. What made you change yore mind?"

"Haven't changed it. Knew that all the time--well, not all the time.

I was millin' you over in my mind quite a bit while you were holdin'

out on me. Couldn't be dead sure whether you were hidin' what you knew just to hurt Hull or because of your own guilt."

"Still, I don't see how you're sure yet. I might 'a' gone in by the window an' gunned Cunningham like you said."

"Yes, you might have, but you didn't. I'm not goin' to have you arrested, Olson, but I want you to stay in Denver for a day or two until this is settled. We may need you as a witness. It won't be long. I'll see your expenses are paid while you're here."

"I'm free to come an' go as I please?"

"Absolutely." Kirby looked at him with level eyes. He spoke quite as a matter of course. "You're no fool, Olson. You wouldn't stir up suspicion against yourself again by runnin' away now, after I tell you that my eye is on the one that did it."

The Swede started. "You mean--now?"

"Not this very minute," Kirby laughed. "I mean I've got the person spotted, at least I think I have. I've made a lot of mistakes since I started roundin' up this fellow with the brand of Cain. Maybe I'm makin' another. But I've a hunch that I'm ridin' herd on the right one this time."

He rose. Olson took the hint. He would have liked to ask some questions, for his mind was filled with a burning curiosity. But his host's manner did not invite them. The rancher left.

Up and down his room Kirby paced a beat from the window to the door and back again. His mind was busy dissecting, a.n.a.lyzing, cla.s.sifying.

Some one had once remarked that he had a single-track mind. In one sense he had. The habit of it was to follow a train of thought to its logical conclusion. He did not hop from one thing to another inconsequently.

Just now his brain was working on his cousin James. He went back to the first day of his arrival in Denver and sifted the evidence for and against him. A stream of details, fugitive impressions, and mental reactions flooded through.

For one of so cold a temperament James had been distinctly friendly to him. He had gone out of his way to find bond for him when he had been arrested. He had tried to smooth over difficulties between him and Jack. But Kirby, against his desire, found practical reasons of policy to explain these overtures. James had known he would soon be released through the efforts of other cattlemen. He had stepped in to win the Wyoming cousin's confidence in order that he might prove an a.s.set rather than a liability to his cause. The oil broker had readily agreed to protect Esther McLean from publicity, but the reason for his forbearance was quite plain now. He had been protecting himself, not her.

The man's relation to Esther proved him selfish and without principle.

He had been willing to let his dead uncle bear the odium of his misdeed. Yet beneath the surface of his cold manner James was probably swept by heady pa.s.sions. His love for Phyllis Harriman had carried him beyond prudence, beyond honor. He had duped the uncle whose good-will he had carefully fostered for many years, and at the hour of his uncle's death he had been due to reap the whirlwind.

The problem sifted down to two factors. One was the time element. The other was the temperament of James. A man may be unprincipled and yet draw the line at murder. He may be a seducer and still lack the courage and the cowardice for a cold-blooded killing. Kirby had studied his cousin, but the man was more or less of a sphinx to him.

Behind those cold, calculating eyes what was he thinking?

Only once had he seen him thrown off his poise. That was when Kirby and Rose had met him coming out of the Paradox white and shaken, his arm wrenched and strained. He had been nonplussed at sight of them.

For a moment he had let his eyes mirror the dismay of his soul. The explanation he had given was quite inadequate as a cause.

Twenty-four hours later Kirby had discovered the dead body of the j.a.panese valet Horikawa. The man had been dead perhaps a day. More hours than one had been spent by Kirby pondering on the possible connection of his cousin's momentary breakdown and the servant's death.

_Had James come fresh from the murder of Horikawa_?

It was possible that the Oriental might have held evidence against him and threatened to divulge it. James, with the fear of death in his heart, might have gone each day into the apartment where the man was lurking, taking to him food and newspapers. They might have quarreled.

The strained tendons of Cunningham's arm could be accounted for a good deal more readily on the hypothesis of a bit of expert jiu-jitsu than on that of a fall downstairs. There were pieces in the puzzle Kirby could not fit into place. One of them was to find a sufficient cause for driving Horikawa to conceal himself when there was no evidence against him of the crime.

The time element was tremendously important in the solution of the mystery of Cunningham's death. Kirby had studied this a hundred times.

On the back of an envelope he jotted down once more such memoranda as he knew or could safely guess at. Some of these he had to change slightly as to time to make them dovetail into each other.

8.45. Uncle J. leaves City Club.

8.55. Uncle J. reaches rooms.

8.55- 9.10. Gets slippers, etc. Smokes.

8.55- 9.20. Olson watching from W. fire escape.

9.10- 9.30. Hulls in Apt.

9.30- 9.40. _X_.

9.37- 9.42. Approximately time Olson heard shot.

9.20- 9.42. Olson busy on roof, with rope, etc. Then at window till 9.53.

9.40- 9.53. James in Apt.

9.44- 9.50. Jack and Phyllis in Apt.

9.55-10.05. Wild Rose in rooms.

10.00. I reach rooms.

10.20. Meet Ellis.

10.25. Call police.

That was the time schedule as well as he had been able to work it out.

It was incomplete. For instance, he had not been able to account for Horikawa in it at all unless he represented _X_ in that ten minutes of time unaccounted for. It was inaccurate. Olson was entirely vague as to time, but he could be checked up pretty well by the others. Hull was not quite sure of his clock, and Rose could only say that she had reached the Paradox "quite a little after a quarter to ten."

Fortunately his own arrival checked up hers pretty closely, since she could not have been in the room much more than five minutes before him.

Probably she had been even less than that. James could not have left the apartment more than a minute or so before Rose arrived. It was quite possible that her coming had frightened him out.

So far as the dovetailing of time went, there was only the ten minutes or less between the leaving of the Hulls and the appearance of James left unexplained. If some one other than those mentioned on his penciled memoranda had killed Cunningham, it must have been between half-past nine and twenty minutes to ten. The _X_ he had written in there was the only possible unknown quant.i.ty. By the use of hard work and common sense he had eliminated the rest of the time so far as outsiders were concerned.

Kirby put the envelope in his pocket and went out to get some luncheon.

"I'll call it a mornin'," he told himself with a smile.

CHAPTER x.x.xIX

KIRBY INVITES HIMSELF TO A RIDE

The Twin b.u.t.tes man had said he would call it a morning, but he carried with him to the restaurant the problem that had become the pivot of all his waking thoughts. He had an appointment to meet a man for lunch, and he found his guest waiting for him inside the door.

The restaurant was an inconspicuous one on a side street. Kirby had chosen it for that reason. The man who stepped into the booth with him and sat down on the opposite seat was Hudson, the clerk whom James had accused of losing the sheets of paper with the j.a.panese writing.

"I've got it at last," he said as soon as he was alone. "Thought he never would go out and leave the key to the private drawer inside the safe. But he left the key in the lock--for just five minutes--while Miss Harriman came to see him about something this morning. He walked out with her to the elevator. I ducked into his office. There was the key in the drawer, and in the drawer, right at the bottom under some papers, I found what I wanted."

He handed to Kirby the sheets of paper found in the living-room of the apartment where Horikawa had been found dead.