“Sedimentary argillite,” Benton says to us and not her. “River clay. The aboriginal people made tobacco pipes out of it, and it cakes on shoes and clothing like cement. After digging at the bone bed the last day Emma was seen alive, no one had cleaned up, including her. They’d walked directly to the chow hall, and when she finally headed to her trailer she would have been extremely muddy, dressed for the weather, including a blue hooded rain jacket that appears to be the one the body has on.”

“At night,” Hahn tells us, “the campground is so dark people use flashlights if they’re walking around because you can’t see a thing unless the moon is full, which it certainly wasn’t that night. Just a soupy darkness described by her colleagues as noisy, like a shower going full blast.”

“It would have been very easy to park a vehicle nearby,” Benton says. “And grab her.”

“Especially if she were incapacitated first,” I point out.

“Unless we’re talking about a person she would go with willingly,” Briggs suggests, and it appears he’s reading and initialing reports.

“I doubt that was possible without her colleagues knowing,” Benton answers him. “Without her mentioning something to someone, and based on interviews that have been relayed to us, based on her e-mails, her voicemails, Emma was completely focused on her profession. She wasn’t seeing anyone romantically, had only professional associations while she was working in the bone beds or the lab. When she left the chow hall that night, she said she was tired. She was turning in and would see everybody in the morning and maybe they’d get lucky and the rain would ease up. She walked back through the campground alone.”

“Any tire tracks or footprints by her trailer?” Briggs asks.

“A sea of viscous mud flooded by deep puddles because of the rain,” Benton says.

“So the thought is the killer got her to open her trailer door?” Briggs sips from a mug, coffee, no doubt, and if no one else were here I’d tell him what I usually do.

He drinks coffee all day long and into the night and then complains about insomnia. During my six-month forensic radiologic pathology fellowship at Dover’s port mortuary, I managed to get him to switch to decaf in the afternoon and to take long walks and hot baths. Old bad habits die hard and new good ones don’t last, Kay; he no doubt would say what he always says when I lecture him.

“The thought is he grabbed her before she got inside,” Benton speculates. “There’s no evidence she ever returned to her trailer, that she actually went inside it. No muddy boots were found, no wet clothing, and the door was ajar, as if she was unlocking it when someone came up behind her.”

“They ever find her keys, her flashlight?” Briggs is looking at us again.