"In that half hour," Sam asked, "how far could she have got?"

"I am not a medium, Detective," Cooper said sweetly. "Adrenaline can have fascinating effects on the human body, and there is evidence that the victim was in fact in a state of considerable emotion. The presence of cadaveric spasm--in this case, the hands contracting into fists at the moment of death and remaining clenched through rigor mortis--is generally associated with extreme emotional stress. If she was sufficiently motivated, which under the circumstances I would imagine she was, a mile or so would not be out of the question. Alternatively, of course, she could have collapsed within yards."

"OK," Sam said. He found a highlighter pen on someone's desk and drew a wide circle around the cottage on the map, taking in the village and Whitethorn House and acres of empty hillside. "So our primary crime scene could be anywhere in here."

"Wouldn't she have been in too much pain to get far?" I asked. I felt Frank's eyes flick to me. We don't ask whether victims suffered. Unless they were actually tortured, we don't need to know: getting emotionally involved does nothing except wreck your objectivity and give you nightmares, and we're going to tell the family it was painless anyway.

"Restrain your imagination, Detective Maddox," Cooper told me. "A tension pneumothorax is often relatively painless. She would have been aware of mounting shortness of breath and an increased heart rate; as shock set in, her skin would have become cold and clammy and she would have felt light-headed, but there is no reason to suppose that she was in excruciating agony."

"How much force went into the stabbing?" Sam asked. "Could anyone have done it, or would it take a big strong fella?"

Cooper sighed. We always ask: could a scrawny guy have done it? What about a woman? A kid? How big a kid? "The shape of the wound on cross section, " he said, "combined with the lack of splitting in the skin at the entry point, implies a blade with a fairly sharp tip. It did not encounter bone or cartilage at any point. Assuming a fairly swift lunge, I would say that this injury could have been inflicted by a large man, a small man, a large woman, a small woman, or a strong pubescent child. Does that answer your question?"

Sam shut up. "Time of death?" O'Kelly demanded.

"Between eleven and one o'clock," said Cooper, examining a cuticle. "As I believe my preliminary report stated."

"We can narrow it down a bit," Sam said. He found a marker and started a new timeline under Frank's. "Rainfall in that area started about ten past midnight, and the Bureau's guessing she was out in it for fifteen or twenty minutes max, from the degree of dampness, so she was moved into shelter by around half past twelve. And she was dead by then. Going by what Dr. Cooper says, that puts the actual stabbing no later than midnight, probably earlier--I'd say she was well on the way to unconscious before the rain started in, or she'd have gone into shelter. If the housemates are telling the truth about her leaving the house unharmed at half past eleven, then that gives us a half-hour window for the stabbing. If they're lying or mistaken, it could've been anywhere between ten and twelve."