Monday Mourning (20 page)

“Yep.”

The hummingbird revved up again.

“The technique can tell you where someone lived?”

“If you have reference samples. In some circumstances, if a subject moved from one geographic region to another, Sr analysis can tell where they were born, and where they spent the last six to ten years of their life.”

The hummingbird gunned it to red-line.

“Drop back and start from the beginning.” I grabbed pen and paper. “Using no word having more than three syllables.”

“There are four stable isotopes of strontium, and one isotope,
⁸⁷
Sr is produced by the radioactive decay of
⁸⁷
Rb. The half-life’s forty-eight point eight billion years.”

“Much slower than Carbon 14.”

“Much slower than my old dog Spud.”

Spud?

“The geology of North America shows tremendous age variation,” Art sailed on, oblivious to my confusion over the dog reference. “For example, the age of the crust varies from less than a million years in Hawaii, to just over four billion years in parts of the Northwest Territories of Canada.”

“Resulting in differences in Sr values in the soil and rock of different regions.”

“Yes. But such differences are also due to variations in bedrock composition.”

“When you use the term value, do you mean the ratio of the unstable strontium to its stable counterpart?”

“Exactly. It’s the ratio of the strontium 87 isotope to the strontium 86 isotope that’s important, not the absolute level of each.”

I let him go on.

“For example, basaltic lavas, limestone, and marble all have very low Sr ratios, whereas those of sandstone, shale, and granite are commonly high. Clay minerals have some of the highest.”

“So differences in geologic age and/or bedrock composition produce variations in Sr isotope ratios in different geographic regions.”

“Precisely. But one final thing to keep in mind is that because ratios are so messy to remember, with all those decimals, we usually compare a measured Sr ratio to the average Sr ratio of the whole Earth. If the measured ratio is greater than this, it yields a positive value. If it’s less than this, it gives you a negative value.”

“What does this have to do with establishing where someone was born?”

“Strontium is an alkaline-earth metal, chemically similar to calcium.”

I made the link. “Strontium is absorbed by plants from the soil and water. Herbivores eat the plants, and on up the food chain.”

“You are what you eat.”

“So the Sr isotope composition of an organism’s bones and teeth will reflect the Sr composition of its diet during the period those body parts were forming.”

“You’ve got it.”

“My grandmother used to worry about strontium in her food.”

“Your granny wasn’t alone. The biological processing of strontium was studied extensively in the 1950s because of the potential for radioactive
⁹⁰
Sr ingestion due to aboveground testing of nuclear weapons.”

A light was going on.

“You’re saying strontium is incorporated into a person’s bones and teeth, much like calcium.”

“Right.”

“And calcium in the human skeleton is replaced on roughly a six-year cycle.”

“Yep.”

“So, like skeletal Ca, skeletal Sr reflects an individual’s diet over the last six years of life.”

“Six to ten,” Art said.

“But Ca levels don’t change in tooth enamel as they do in bone. Once laid down, enamel is stable.”

“And the same is true of Sr. So dental enamel continues to reflect the average dietary Sr isotope composition ingested when the tooth was formed.”

“So if someone relocated from the place in which she was living when her teeth were forming, that individual’s dental and skeletal Sr levels would differ. If she stayed put, those levels would remain similar.”

“Precisely. Enamel values suggest place of birth and early childhood. Bone values suggest place of residence during the last years of life.”

A thought stopped me in midscribble.

“Doesn’t our food come through national and international networks these days?”

“We drink local water, at least most of the time.”

“True. Tell me what you did with my specimens.”

“After removing all extraneous materials, we ground them. Then we separated out the Sr by ion-exchange chromatography, analyzed the purified Sr using thermal ionization mass spectrometry, and collected the Sr ratios by multicollector dynamic analys—”

“Art.”

“Yes?”

“What did you find?”

“One of your three saw a bit of the world.”

“G
O ON
.”

“First, let’s talk teeth. Two of your individuals overlap in their dental Sr values.”

“Which two?”

Paper rustling.

“Let’s see… 38426 and 38427. For them I’d expect a childhood diet with an average Sr value of plus ninety to plus one hundred five. But 38428 is statistically distinct. The Sr isotope composition of that individual’s dental sample suggests a childhood diet with an average Sr value of plus fifty to plus sixty.”

“Meaning 38428 was not born in the same region as the other two?”

“Correct.”

“Can you tell where she’s from?”

“That’s where it gets interesting. Last year we had a case of jumbled remains from a barrel found in some hophead’s basement in Detroit. Police knew the victims were business associates of the drug dealer who owned the house, but wanted the bones sorted into individuals. None had dental work, all were black, in their mid-twenties, and about the same size. One of the three was born in north-central California, one was from Kansas, and the other was local Michigan talent.

“We didn’t have control groups from the three areas in question, so we had to infer the isotope composition of the dietary Sr from the bedrock geology in each region, then work back to the various bones in the barrel. You still there?”

“I’m here.”

“Someone who spent their childhood in north-central California should have Sr values in the range of plus thirty to plus sixty.” Rustle. “That’s exactly where 38428 falls.”

For a moment I was taken aback.

“Meaning my girl’s from California?”

“Meaning she could be. If you have no other ideas, it’s as good a starting point as any. Of course, she could be from another region with similar bedrock geology.”

“And my other unknowns?”

“A couple of years back we had a case involving commingled remains recovered from a common grave in Vietnam. The army had IDs for the two soldiers, but wanted the bones separated into individuals. One soldier had grown up in northeastern Vermont. The other was from Utah.”

Art gave me no chance to interrupt.

“A study of the Sr isotope composition of the groundwater near St. Johnsbury in Vermont suggested values in the range of plus eighty-four to plus ninety-four. The teeth from one of the soldiers produced Sr values smack-dab in that range.”

“The Vermonter.”

“Yes. The teeth of 38426 and 38427 produced identical values.”

“Meaning these girls were from Vermont?”

“Not so fast. The same rock formations extend across the border into Quebec. What I’m suggesting is that the Sr values of your other two girls are consistent with what I’d expect from people born in the region where the remains were found.”

“The Montreal area.”

“Yes. Now let’s talk bones. For 38426 and 38427, the Sr values in their teeth are similar to the Sr values in their bones.”

“Suggesting they didn’t stray too far from home.”

“Right. But 38428 is a different story.”

I waited.

“Her skeletal Sr values are higher than her dental Sr values. What’s more, her skeletal Sr values are very similar to the skeletal Sr values for 38426 and 38427.”

“The Quebec stay-at-homes.”

“Yes.”

I took several moments to digest that.

“You’re suggesting 38428 was raised in one place, but spent the last few years of her life in another.”

“Looks that way.”

“That she may have grown up in north-central California.”

“Or in an isotopically similar region.”

“But later she may have moved to Quebec or Vermont.”

“Or to an isotopically similar region.”

I couldn’t wait to phone Charbonneau.

“This is terrific, Art.”

“We aim to please. Let me know when you get these ladies ID’d.”

I was so excited I misdialed and had to punch the numbers a second time.

Charbonneau was out. So was Claudel.

Were they ever in?

I left a verbal message with the receptionist, then a numeric one on Charbonneau’s pager.

Back to my lab.

Anticipating what I might find, I carried the Dr. Energy girl’s skull and jaw to the scope.

There they were. Five tiny grooves, two above and three posterior to the auditory canal on the right temporal bone. Magnified, the cuts looked like those on 38427.

I could see nothing on the jaw or on any of the other cranial bones.

Sweet Jesus. What had been done to these girls?

Anne phoned at one-fifteen, her voice sounding listless and flat. After apologizing for being lousy company all week, she told me she was thinking of leaving. Said she didn’t want to impose on my hospitality any longer.

I assured her that she was not imposing. I also assured her that I was enjoying her company tremendously. Given her current mood, the latter was a stretch, but I encouraged her to think in terms of staying until she decided on a better place to go.

Charbonneau phoned at one-forty.

“Cibole!
It’s colder than a witch’s tit out there.”

Not all of Charbonneau’s expressions were Texan in origin.

“You ran the CPIC search?”

“I did.”

I heard cellophane.

“Since we don’t know if the two without dental sealant died before or after the one with the sealant, I ran those cases two ways. First I searched disappearances reported in the nineties.”

“Makes sense, given the Carbon 14.”

“Some came close, but no cigars.”

Charbonneau sounded like he was eating something involving caramel or taffy.

“Then I left the date of disappearance open. Got what I expected, given no dentals, no details, and no dates.”

“Lots of hits?”

“List from here to East Bumfuck.”

“What about 38428?”

“Pulled up everything back to 1980. Broken wrist cut the numbers down. Again, a few came close, but no matches. Sure would help to know where the kid lived.”

“How about north-central California?”

“Yeah. Like that.”

“I’m serious.”

All crinkling and chewing stopped.

“You’re kiddin’.”

Simplifying the biochemistry and geophysics, I told Charbonneau what I’d learned from Art Holliday.

“Luc’s gonna shit his Fruit of the Looms.”

“You’ve got to send her descriptors south of the border.”

“NCIC. Done. I’ll also roll them by the Vermont and California State Police.”

“It’s a long shot.”

“Can’t hurt anything.”

“Except your partner’s shorts.”

Charbonneau laughed. “I’ll tell him you said that.”

“There’s something else.”

“Make my day.”

I described the nicks and grooves.

“And you think the marks were made by a scalpel?”

“Or an extremely sharp, fine-edged blade.”

“You’re talking all three skeletons?”

“Yes. Though the marks on the shrouded burial differ from those on the other two.”

“Differ how?”

“They’re cruder. And there’s more chipping along the edges.”

“Meaning they were made by a different tool?”

“Maybe. Or maybe they were made after the bone had dried out. Or maybe they’re not the result of cutting at all. Maybe they’re postmortem artifacts mimicking cut marks.”

“Scratches caused by dragging or rolling or something?”

“Maybe.”

“You don’t sound convinced.”

“There seems to be a pattern.” I stopped, picturing the skulls and jaws in my mind. “The marks circle the right ear opening.”

“On which skeleton?”

“On all three.”

“And nothing anywhere else?”

“No.”

“Holy crap. You think someone was slicing off ears?”

The thought had occurred to me.

“I don’t know.”

After telling LaManche what I’d learned from Art Holliday, I spent the rest of the afternoon with my pizza basement girls. That’s how I’d come to think of them. My girls. My lost girls.

I reexamined every bone, bone fragment, and tooth. I studied the dental and skeletal X-rays. I rescreened the soil. I pored over the buttons.

When at last I sat back, the windows were dark and the halls were quiet. The clock said five-twenty.

I’d learned not one damn additional thing.

I closed my eyes.

I felt sadness over my failure to give names to these girls. Anger over my failure to satisfy Claudel. Frustration over my failure to understand the buttons. Guilt over my failure to spot the cut marks before Bergeron pointed them out.

How could I have missed those marks? Yes, I’d been interrupted many times. Yes, I’d been working on different aspects of the case. Yes, the marks were almost invisible. Yes, at least one skull was fragmented. But how could something that important have escaped my attention?

Failure, failure everywhere and not a drop to drink.

Failure with Anne.

Failure with Ryan.

“Ryan,” I snorted.

“Yes?”

My eyes flew open.

Ryan was standing in the doorway, coat finger-hooked over one shoulder. He was regarding me with an expression I couldn’t interpret.

Ryan raised his free hand, palm out.

“I know. What are
you
doing here? Right?”

I started to speak. Ryan cut me off.

“I work downstairs.” Ryan grinned. “I’m a cop.”

I sat forward and tucked my hair behind my ears.

“Do you have news on Louise Parent?”

“No.”

“Have you found Rose Fisher?”

The grin evaporated. “No. It doesn’t look good.”

“You think she’s dead?”