It was from Farriss.

It read: If any clues, advise immediately.

Willis digging hard.

Letter of instruction follows.
FARRISS.
The girl folded the message, thrust it in her jacket-pocket, then turning to the marshal and Westcott, gave each a firm hand.
"You've both been more than kind," she said gratefully.
"Hell, ma'am," Dan deprecated, "that warn't nothin'!" And he hurried into the street as loud cries sounded outside.
"Good night, Miss Donovan," Westcott said simply.

"If you are ever frightened or in need of a friend, call on me.