No murder investigation is complete without a healthy assortment of suspects. Katy Devlin is found near an archeological dig, so maybe some of those archeologists did it… Maybe digging up old bones isn't good enough for them… Maybe they want to put some bodies of their own in the ground. Maybe… but maybe not.
None of the archeologists actually have anything to do with the crime. There's Dr. Ian Hunt, the scatterbrained site director; Sean, who lost his trowel, an implement that turns out to be part of Katy's murder; and Mel, seemingly the only female (whom Rob instantly finds attractive).
Finally, there's Mark Hanly, who is handsome and intelligent and passionate. Cassie and Mel seem to like him so, of course, Rob hates him, mainly because he makes him feel "violently insecure" (2.40). Mark really wants to preserve the dig site, and he practically worships the findings there, camping out in the woods and pouring wine on the ground as an offering. He might be a little nutty, but—bummer for Rob—he's definitely not a murderer.