And always, the central question: When? A decade ago? A century?

By the time I reached home, a headache was cranking into high gear, and I was hungry enough to eat Lithuania. Except for granola bars and diet sodas, I'd consumed nothing all day.

After showering, I nuked a frozen Mexican dinner. As I dined with Letterman, I thought about Anne. Anne would understand. Let me vent. Say comforting things. I'd just collected the handset, when it rang in my hand.

"How's Birdie?" Anne.

"You're calling about my cat?"

"I don't think the little guy gets enough attention."

The little guy was beside me on the couch, staring at the sour cream oozing from my burrito remains.

"I'm sure Bird would agree."

Setting my dinner on the coffee table, I scooped a dollop of cream and offered a finger. Birdie licked it clean and refocused on the plate.

"How about you?"

I was lost. "How about me what?"

"Are you getting enough attention?"

Though Anne has the instincts of a NAVSAT, she couldn't have known of my anxiety over Ryan.

"I was just about to call you," I said.

"I'm not," she continued, not really listening to my answer.

"What are you talking about?"

"Tom-Ted."

Anne is married to an attorney named Tom Turnip. When Tom was a second-year a.s.sociate with his firm, a senior partner had addressed him as Ted for an entire month. He'd been Tom-Ted ever since.

"What about TT?"

"Guess?"

Though I wanted to be sympathetic, I was far too exhausted for puzzles.

"Please just tell me."

"Good idea. I'll be there tomorrow."

7.

EIGHT HOURS LATER MY STATE OF MIND WAS MUCH IMPROVED. The headache was gone. The sun was shining. My best friend was coming. The headache was gone. The sun was shining. My best friend was coming.

Maybe. Anne has a way of changing her mind.

Speaking of changing minds, Ryan was right. Evidence as to postmortem interval, or PMI, was at the heart of the debate with Claudel.

Crunching cornflakes, I considered the problem.

At this point I knew 38426 and 38427 had come from shallow graves in a dry bas.e.m.e.nt. The skeletons were devoid of flesh but well preserved, with no surface cracking or flaking.

Mental checklist. What other data are useful for pinpointing PMI with dry bones?

Deterioration of a.s.sociated materials. I had none.

a.n.a.lysis of insect inclusions. I had none.

Bird nosed toward my cereal, hoping to score milk. I displaced him to a chair.

Should I move on to 38428, or should I focus on establishing PMI?

Birdie oozed back onto the table. Again, I lifted him down.

If I found evidence that the burials were old, I could relax and notify the archaeologists. On the other hand, if I found evidence that the deaths were recent, as I suspected, the coroner would insist on an investigation, and Claudel would have no choice. He and Charbonneau could start the legwork while I a.n.a.lyzed the third set of remains.

As I poured coffee, Birdie launched a third sortie. I relocated him again, somewhat less gently.

OK. I had no artifacts or bugs. What options did that leave?

I knew that the elemental composition of bone changes over time. The amount of nitrogen decreases, the amount of fluoride increases. But these shifts are too slow to be of use in evaluating the age of modern remains.

I'd read studies that focused on radiography, histology, chemical reaction, and isotope content. I was aware of research that pointed to amino acids as useful in distinguishing recent from ancient bone.

But a myriad of factors influence biochemical and physical processes. Temperature. Ground moisture. Oxygen tension. Microbial activity. Soil pH. No technique is reliably accurate. Once the flesh and bugs move on, PMI becomes the Bermuda Triangle of forensic anthropology.

I could think of only one test that might yield definitive results. But it would take time and cost money, and only a handful of labs performed it. Given the current financial climate, I knew it would be a hard sell to LaManche.

But it was worth a shot.

Placing my bowl on the floor, I gathered my purse and laptop and set off.

In my office, the message light remained obstinately dark.

The morning meeting was routine. A man dead of fumes from a malfunctioning s.p.a.ce heater. An alcohol-related traffic death. An autoerotic with a faulty escape knot in his noose. A charred body in a burned-out motor home.

Pelletier caught the fire victim. Though the remains were thought to be those of the trailer's owner, he asked that I be available in case things got dicey.

As the others filed out, I turned to LaManche.

"May I speak with you a moment?"

"Mais, oui." LaManche folded back into his seat. LaManche folded back into his seat.

"I've examined two of the skeletons from the pizza parlor bas.e.m.e.nt."

When LaManche raised his brows, the lines in his flesh elongated and deepened. He seemed suddenly older, more worn than I remembered. Was it the cold morning light from the windows behind me? Was LaManche unwell? Had I simply not noticed until this moment?

"The two victims I've examined are young and female," I said. "I'm certain the third is a young woman as well."

"You use the word 'victim.'"

"They're kids and they're dead."

LaManche's melancholy eyes did not flinch at my sharpness.

"But I've found no signs of violence," I admitted.

"Monsieur Claudel feels these remains are probably not recent."

"The restaurant owner found b.u.t.tons that could be nineteenth century."

"Could be?" The brows rose again.

"Claudel took them to the McCord."

"You are unconvinced?"

"Even if the b.u.t.tons are genuine, it's unclear whether they were a.s.sociated with any of the skeletons. Their presence in the bas.e.m.e.nt could have any number of explanations."

LaManche sighed and pulled his ear. "Monsieur Claudel also told me that the building is more than a hundred years old."

"Claudel has researched the property?" I felt heat flush my face. "He has not shared that information with me."

"Construction took place over a century ago."

I have a flash point temper. My father's temper. Along with drink, Daddy's fury sometimes ruled him. I grew up with the impact of those outbursts.

Like Daddy, I succ.u.mbed to the lure of the bottle. Unlike him, I walked away from booze. Also unlike him, I learned to control my temper. When fire simmers inside, outside I grow deadly calm.

"Did Monsieur Claudel not realize that such information is relevant to my task?" I asked, my voice glacial.

"I am certain he will inform you in detail."

"During my lifetime?"

"Do not grow defensive. I am not fighting you."

I drew a deep breath.

"There is one test which might resolve the question."

"Tell me."

"You've heard of Carbon 14 dating?"

"I know it is used to a.s.sign age to organic materials, including human bone. I do not know how it works."

"Radiocarbon, or Carbon 14, is an unstable isotope. Like all radioactive substances, it decays by releasing subatomic particles at a uniform rate."

LaManche's eyes stayed heavy on mine.

"In about 5,730 years half of a population of radiocarbon atoms will have reverted to nitrogen."

"That is the half-life."

I nodded. "After 11,460 years, a fourth of the original amount of radiocarbon remains. After another 5,730 years, only an eighth remains, and so on."

LaManche did not interrupt.

"The amount of radiocarbon in the atmosphere is really tiny. There's only about one radiocarbon atom for every trillion stable carbon atoms. Radiocarbon is constantly being created in the upper atmosphere by cosmic bombardment of nitrogen. Some of the nitrogen converts to radiocarbon, which immediately oxidizes to CO2. That CO2 works its way down into the biosphere, where it's taken up by plants. Since humans, animals, and plants comprise the same food chain, as long as they are alive they have a constant amount of radiocarbon in them. The actual amount is gradually decreasing due to radioactive decay, but is being replenished through food intake, or through photosynthesis in the case of plants. This equilibrium exists as long as an organism is alive. When it dies, decay becomes the only active process. Radiocarbon dating is a method that determines the point in time at which this disequilibrium started." works its way down into the biosphere, where it's taken up by plants. Since humans, animals, and plants comprise the same food chain, as long as they are alive they have a constant amount of radiocarbon in them. The actual amount is gradually decreasing due to radioactive decay, but is being replenished through food intake, or through photosynthesis in the case of plants. This equilibrium exists as long as an organism is alive. When it dies, decay becomes the only active process. Radiocarbon dating is a method that determines the point in time at which this disequilibrium started."

LaManche raised both palms in a gesture of skepticism. "Five-thousand-plus years. How can such a slow process be of value with recent remains?"

"A fair question. It's true that Carbon 14 dating has been used primarily by archaeologists, and has been shown to be quite reliable. But the technique is based on a number of a.s.sumptions, one of which is that the atmospheric level of radiocarbon has remained constant over time. Data inconsistent with that a.s.sumption can actually be used to give the process wider applicability."

"How so?"

"That's where it gets interesting. Studies have doc.u.mented significant anomalies in radiocarbon data for certain time periods. Two perturbations have taken place over the past eighty years, both of which were caused by human activity."

LaManche leaned back, interlaced his fingers, and laid his hands on his chest. A hint for brevity? I did some mental abridgment.

"The period from about 1910 to 1950 is characterized by a decrease of atmospheric radiocarbon, probably due to the release into the atmosphere of the products of combustion of fossil fuels such as oil, coal, and natural gas."

"Why?"

"Because of their great age, fossil fuels contain no detectable radiocarbon. They are said to be dead. Since the combustion of these fuels releases carbon dioxide devoid of radiocarbon, the relative amount of Carbon 14 in the atmosphere drops."

"Oui."

"But beginning about 1950, the atmospheric testing of thermonuclear weapons reversed this downward trend."

"The radiocarbon in living things increased."

"Dramatically. From 1950 to 1963, the values rose to about 85 percent above contemporary reference levels. In 1963, an international agreement halted atmospheric nuclear testing by most nations, and biospheric radiocarbon levels began settling into a new equilibrium."

"Such folly." LaManche wagged his head sadly.

"These permutations are known as the fossil fuel and atomic bomb effects."