He was being paid to kill three doctors in a single day—doctors, when he had never killed a doctor before—so he knew there was something that linked them, something the cops would pick up on when they found Weatherby in the trunk of his car and Elisabeth Yarbeck beaten to death in her bedroom! He'd made private contacts with rare off-worlders at the port-of-entry canyon – openings and landing pads in the sheer cliff wall where carefully guarded ships hauled Tleilaxu products to waiting Heighliners in orbit!