All of the staff on the dig are valid person's of interest.Here' another one ...Kyle.
Now I really believe Kyle is just a good comic relief type story character but I managed to come up with another convoluted theory. Kyle is really intense about his gaming probably because he has no love life because he's so damn hairy.If that realization has finally hit him and if he's anything like my friend in my previous comment he might be looking into laser hair removal. I know somebody who works in that business and she told me in extreme case the first session could cost $1000 plus. And after all is said and done it could be up to $10,000. Since Kyle is Ricky's friend I'm sure Ricky isn't discreet about what went on at the dig. If Kyle needs money well he might have figured out a way. Also his clueless act makes him the perfect person eavesdrop on Killian and Ricky's conversation..... OK you can stop laughing my lame theory