How Long Did the Killer Interact With Dwayne?

The killer had used Dwayne's own belt to restrain his hands behind his back. The question that I would start looking at is how long did the offender interact with Dwayne? And of course, Patty is also part of this, but right now I'm just focusing on Dwayne. Does this suggest a possibility that the killer met up with Dwayne and Patty at a different location and then met them here or got into the car with them?"