It had occurred to him that if they believed Barney dead, they might reveal something of their purpose in the attack.

Concealment, he felt vaguely, would serve merely to sharpen their suspicion of him.

It had seemed very important to Casey that these three should not know that Barney was probably well on his way to Barstow by now.
Barney in Barstow would mean Barney bearing news that Casey Ryan was undoubtedly murdered by outlaws in the Panamints; which would mean a few officers on the trail, with Barney to guide them to the spot.

Paw and Hank and Joe--outlaws all, he would have sworn would get what Casey called their needin's.

His jaw muscles tightened when he thought of that, and the prospect held him quiet under Joe's injustice.
"I can prove anything I'm asked to prove when the time comes," he said sourly, and began to roll himself a cigarette, since his pipe had gone out.