Convict labor is at the root of the disastrous ending of DEVIL MAKE A THIRD:

from page 353:

Buck began to tap on the table for emphasis. "Remember, he's a Georgia contractor?"

Jeff nodded.

"Remember how long he'd been on the foundation when I placed the bets?"

Jeff tried to think. "Around ten days," he said.

"That's right. Well, on that day I happened to see one of the workmen rubbing salve on a scar on his ankle." He paused. "It went all the way around his leg."

Jeff's forehead wrinkled. "Convict?"

Buck nodded.