Let me see if I'm understanding you correctly (I'm not sure if I'm reading your post correctly). Are you saying that your sleuthing coworker found out that the Romeo coworker knows but isn't interested? If that's the case, are you certain that Romeo would want to tell your sleuth? Could there be a reason that they wouldn't want to reveal that information to the sleuth? And finally, is the sleuth a man or woman?
You don't have to answer any of those questions, of course. I'm just trying to sort through your issue.