You follow up your previous question with: "I've heard Stormwind is handing out rewards for any information on the case around here." The thug looks conflicted, unsure of whether to take you up on this or not. Eventually, he says, "Sure, take me where they're giving out the rewards." You can't very well keep asking him questions by yourself given how this most recent ploy ended, so you take him to the Stormwind officials by the wagon you saw on your way into Westfall. "I surrender," he says, putting up his hands. "Great," says the most smartly-dressed of the investigators as the other two awkwardly tie up the thug. "That'll save you a headache later." "So what do we do with him, Laine?" asks the investigator who's worse at tying up the thug. "We find out what he knows," says Laine.
Try to keep the thug calm. That should make him easier to interrogate. Try to force a confession out of him before he gets too comfortable. See what Laine's plan is. Let him deal with the thug...at least to begin with.