Grave Secrets

I glanced at Galiano. He waved me into the chair.

“Would you prefer that I speak English?” Minos asked.

“If you don’t mind.” I felt like a dunce, but my Spanish was shaky, and I wanted to fully understand his explanation.

“What do you see?”

“It looks like a wire with a pointed end.”

“You’re looking at an uncut hair. It is one of twenty-seven included in the sample marked ‘Paraiso.’”

Minos’s English had an odd up-and-down cadence, like a calliope.

“Notice that the hair has no distinctive shape.”

“Distinctive?”

“With some species shape is a good identifier. Horse hair is coarse, with a sharp bend near the root. Deer hair is crinkly, with a very narrow root. Very distinctive. The Paraiso hairs are nothing like that.” He readjusted his glasses. “Now check the pigment distribution. See anything distinctive?”

Minos was fond of the word distinctive.

“Seems pretty homogenous,” I said.

“It is. May I?”

Withdrawing the slide, he moved to an optical scope, inserted it, and adjusted the focus. I rolled my chair down the counter and peered through the eyepiece. The hair now looked like a thick pipe with a narrow core.

“Describe the medulla,” Minos directed.

I focused on the hollow center, the region analogous to the marrow cavity in a long bone.

“Resembles a ladder.”

“Excellent. Medullar form is extremely variable. Some species have bipartite, or even multipartite medulla. The llama group is a good example of that. Very distinctive. Llamas also tend to have large pigment aggregates. When I see that combination, I immediately think llama.”

Llama?

“Your samples have a single-ladder medulla. That’s what you’re seeing.”

“Which means cat?”

“Not necessarily. Cattle, goats, chinchilla, mink, muskrat, badger, fox, beaver, dog, indeed many forms can have a single-ladder medulla in the fine hairs. Muskrat has a chevron-scale pattern, so I knew it wasn’t muskrat.”

“Scales?” Galiano asked. “Like fish?”

“Actually, yes. I’ll explain scales shortly. Cattle hairs frequently have a streaky pigment distribution, often with large aggregates, so I eliminated cattle. The scales didn’t look right for goat.”

Minos seemed to be talking more to himself than to us, reviewing verbally the thought process he’d used in his analysis.

“I also excluded badger because of the pigment distribution. I ruled out—”

“What could you not rule out, Senor Minos?” Galiano broke in.

“Dog.” Minos sounded wounded by Galiano’s lack of interest in mammalian hair.

“Ay, Dios.” Galiano puffed air out of his lips. “How often would dog hair turn up on clothing?”

“Oh, it’s very, very common.” Minos missed Galiano’s sarcasm.

“So I decided to double-check myself.”

He walked to a desk and pulled a manila folder from a slotted shelf.

“Once I’d eliminated everything but cat and dog, I took measurements and did what I call a medullary percentage analysis.”

He withdrew a printout and laid it on the counter beside me.

“Since cat and dog hair is so frequently encountered at crime scenes, I’ve done a bit of research on discriminating between the two. I’ve measured hundreds of dog and cat hairs and set up a database.”

He flipped a page and pointed to a scatter graph bisected by a diagonal slash. The line divided dozens of triangles above from dozens of circles below. Only a handful of symbols crossed the metric Rubicon.

“I calculate medullary percentage by dividing medullar width by hair width. This graph plots that figure, expressed as a percentage, against simple hair width, expressed in microns. As you can see, with few exceptions, cat values cluster above a certain threshold, while dog values lie below.”

“Meaning that the medulla is relatively wider in cat hairs.”

“Yes.” He beamed at me, a teacher pleased with a bright student. Then he pointed to a clump of asterisks in the swarm of triangles above the line.

“Those points represent values for randomly selected hairs from the Paraiso sample. Every one falls squarely with the cats.”