Barney Cousins: You don't care if she's alive or dead anymore.
Jeff Harriman: Yes I do.
Jeff Harriman: No you don't. You're just scared that without the search you won't know who you are. Who is Jeff Harriman, if he's not the guy looking for Diane? Can you really walk away from finally knowing the answer?
Cop at Gas Station: Had you had a fight recently?
Jeff Harriman: Not a fight, a thing.
Cop at Gas Station: ...A thing?
Jeff Harriman: Yeah, a thing, don't you have a girlfriend?
Cop at Gas Station: Yeah. And what you think is a thing, you can bet your life she thinks is a fight.
Barney Cousins: To me, to kill is not the worst thing you can imagine. There is more.
Jeff Harriman: I just want to know what happened to Diane.
Barney Cousins: Then you'll want to listen to the story, and you'll want to listen carefully because sometimes the Devil is in the details.
Helene Cousins: Look, he put up a new one. I heard him on Talk Radio. Every month he puts up a new one.
Barney Cousins: Every 30 days, you could set your watch by it.
Helene Cousins: He must have loved her very much.
Barney Cousins: ...I do admire his perseverance.
Answer: He is a crew member lying in the road directly behind the brown G.R.S. Dye Works semi-truck (presumably trying to remain hidden from the camera's view), and we even see his right hand waving off the traffic ahead of him (00:22:05).