Detective Pearson brushed back a strand of rain-glistened hair and sighed. "Well, it can't hurt to share information. It's a nice change. Usually, the boys want to use my notes, but they won't share theirs." She looked at Frost. "Not to cast aspersions on the guys."

Jane laughed. "This guy's different. He shares everything, except his potato chips."

"Which you just steal anyway," said Frost.

"I'll email you what I've got as soon as I get home," said Detective Pearson. "You can get Jodi's autopsy report directly from the ME."

"Which doc did it?"

"I'm not familiar with all the pathologists there. It was a big man. Big voice."

"Sounds like Dr. Bristol," said Frost.

"Yes, that's his name. Dr. Bristol. He did her autopsy last Tuesday." Pearson took out her car keys. "There were no surprises."

THAT WAS THE THING ABOUT SURPRISES; YOU NEVER KNEW WHEN ONE would turn up that could change the course of an investigation. Jane devoted the next afternoon to hunting for just such a surprise among the files that Andrea Pearson had emailed her. Sitting at her computer, the remains of her lunch scattered across her desk, she clicked through page after page of witness statements and Detective Pearson's notes. Jodi Underwood had lived in the same Brookline house for eight years, a house she'd inherited from her parents, and was known to be a quiet and considerate neighbor. She had no enemies and no current boyfriends. On the night of her murder, none of the neighbors recalled hearing any screams or loud noises, nothing to indicate someone was fighting for her life.

A blitz attack was what Pearson called it, a takedown so rapid that the victim had no chance to fight back. The crime scene photos supported Pearson's description. Jodi's body was found in the foyer lying on her back with one arm stretched toward the front door, as if to pull herself out and over the threshold. She was dressed in striped pajamas and a dark blue robe. One slipper was still on her left foot; the other lay only a few inches away. Jane had slipper scuffs just like them, tan suede with fleece on the inside, ordered from L.L.Bean. She'd never again be able to wear them without thinking of this photo of a dead woman's feet.

She moved on to the autopsy report, dictated by Maura's colleague, Dr. Bristol. Abe Bristol was a larger-than-life personality with a loud laugh and big appet.i.tes and sloppy eating habits, but in the morgue he was every bit as detail-minded as Maura. Though the ligature was not found at the scene, the bruises on the victim's neck told Bristol that cord and not wire was used. Time of death was sometime between eight P.M. and two A.M.

Jane clicked through pages describing the internal organs (all healthy) and the genital exam (no evidence of trauma or recent s.e.xual activity). No surprises yet.

She moved on to the list of clothing: women's striped pajamas, top and bottom, 100 percent cotton, size small. Bathrobe, dark-blue velour, size small. Women's fleece slipper scuffs, size seven, brand: L.L.Bean.

She clicked to the next page. Scanned down the list of trace evidence that had been turned over to the crime lab and saw the usual fingernail clippings, combed pubic hairs, orifice swabs. Then she focused on the items at the bottom of the page.

Three hair strands, white/gray, possibly animal, approximately three to four centimeters long. Collected from victim's bathrobe, near hem.

Possibly animal.

Jane thought of Jodi's stark wood floors and sleek Swedish furniture, trying to recall seeing any signs that a house pet lived there. A cat, perhaps, who'd brushed up against that blue velour bathrobe. She picked up the phone and called Jodi's sister.

"She loved animals, but she didn't have any pets, unless you count that goldfish who died a few months ago," Sarah said.

"She never had a dog or a cat?" Jane said.

"She couldn't. She was so allergic that if she just got near a cat, she'd start to wheeze." Sarah gave a sad laugh. "When she was a kid, she dreamed of being a veterinarian and she volunteered at the local animal hospital. That's when she got her first asthma attack."

"Did she own any fur coats? Maybe something with rabbit or mink?"

"Not a chance. Jodi belonged to PETA."

Jane hung up and stared at the words on her computer. Three hairs, possibly animal.

And she thought: Leon Gott had cats.

"THESE THREE HAIR STRANDS present an interesting puzzle," said Erin Volchko. A veteran Boston PD criminalist specializing in hair and fibers, Erin had tutored dozens of detectives over the years, guiding them through the intricate a.n.a.lysis of carpet fibers and hair strands, pointing out the differences between wool versus cotton, synthetic versus natural, plucked hair versus cut. Although Jane had peered into the microscope many times, examining strands from countless crime scenes, she would never have Erin's knack for distinguishing one strand from another; all blond hairs looked alike to Jane.

"I've got one of the hairs under the scope now," said Erin. "Have a seat and I'll show you my problem."

Jane settled on the lab stool and looked into the double-headed teaching microscope. Through the eyepieces, she saw a strand that stretched diagonally across the field of view.

"This is Strand Number One collected from Ms. Underwood's blue bathrobe," said Erin, looking through the other pair of eyepieces. "Color: white. Curvature: straight. Length: three centimeters. You can see the cuticle, cortex, and medulla very clearly. Focus first on the color. See how it's not quite uniform? It seems to get paler as you reach the tip, a feature that's called banding. Natural human hair tends to be of uniform color throughout the entire strand, so this is the first clue we're dealing with something that's not human. Now look at the medulla, the central pipeline running through the length of the strand. This medulla is wider than in human hair."

"So what kind of hair is this?"

"The outer layer of cuticle gives us a pretty good idea. I've taken photomicrographs. Let me show you." Erin swiveled around to the computer on her desk and tapped on the keyboard. A magnified image of the hair appeared on-screen. The surface of the strand was covered with slender triangular scales, layered like armor.

"I'd describe these scales as spinous," said Erin. "See how they lift up slightly, as if about to peel away, like little petals? I love how intricate everything looks under high magnification. A whole new universe that we can't see with the naked eye." Erin smiled at the screen as if viewing a foreign city she wished she could visit. Trapped all day in this windowless room, her crime beat was these microscopic landscapes of keratin and protein.

"So what does it mean?" asked Jane. "The fact it's got spinous scales?"

"It confirms my first impression that it's not human. As for species, this scale shape is characteristic of mink, seals, and house cats."

"Common things are common. So I'm guessing this is from a house cat."

Erin nodded. "I can't say it with one hundred percent certainty, but a cat is the most likely source. A single cat sheds hundreds of thousands of hairs in a single year."

"Holy cow. That's a lot of vacuuming."

"And if you've got more than one cat in the house, or dozens of them like some of those cat h.o.a.rders, imagine how many hairs that adds up to."

"I don't want to."

"I saw one forensic study that showed it's impossible to enter a residence where a cat lives without picking up some of its hair. Most American households have at least one cat or dog, so who knows how this particular hair got transferred to the victim's bathrobe? If she didn't have a cat herself, she could have been around a friend's cat."

"Her sister says the victim was severely allergic and avoided animals. I'm wondering if she picked up these hairs from a secondary source. The killer."

"And you think this killer transferred them from the Leon Gott crime scene."

"Gott had two cats and a dog, so his house was like a fur factory. I got covered in cat hair just walking through the place. The killer would have picked up hairs, too. If I collected a few hairs from Gott's cats, can you run DNA comparisons with these three strands?"

Erin sighed and slid her gla.s.ses up on her head. "I'm afraid DNA would present a bit of a problem. All three of these strands from Jodi Underwood's bathrobe were shed during the animals' telogen phase. These hairs have no root tags, ergo no nuclear DNA."

"What about under the microscope? Just a visual comparison?"

"That would only tell us we're looking at white hairs that might be from the same cat. Not good enough as proof in court."

"Is there any way I can prove these hairs were transferred from Gott's house?"

"Possibly. If you spend any time around cats, you'll notice how much they clean themselves. They're constantly grooming, and every time they lick their own hair, they shed epithelial cells from their mouths. We might be able to get mitochondrial DNA markers off these strands. I'm afraid it'll take weeks to get back the results."

"It would be proof, though?"

"Yes, it would be."

"Then I guess I need to collect some cat hairs."

"Pulled directly from the animal itself, so we can harvest root material."

Jane groaned. "That's not going to be easy, since one of the cats doesn't want to be caught. He's still somewhere in the victim's house, running loose."

"Oh dear. I hope someone's feeding him."

"Guess who goes over there every single day to leave food and water and change the litter box?"

Erin laughed. "Don't tell me. Detective Frost?"

"He claims he can't stand cats, but I swear he'd run into a burning building just to save a kitty."

"You know, I always liked Detective Frost. He's such a sweetie."

Jane snorted. "Yeah, makes me look like a b.i.t.c.h in comparison."

"What he needs is to find himself another wife," said Erin as she removed the microscope slide. "I wanted to set him up with one of my girlfriends, but she refuses to date cops. Says they have control issues." She placed a new slide under the microscope. "Okay, let me show you another hair collected from the same bathrobe. This is the one that's got me completely stumped."

Jane settled back onto the lab stool and peered into the eyepiece. "It looks like the first strand. What's different about it?"

"At first glance, it does seem similar. White, straight, about five centimeters. It has the same color banding that tells us this is probably not human. Initially I thought it was also from Felis catus, a house cat. But when you examine it at 1500X, you'll see it's from a very different origin." She swiveled back to her computer and opened a second window on the screen, showing a different photomicrograph. She arranged the two images side by side.

Jane frowned. "The second hair looks nothing like a house cat's."

"The cuticular scales are very different. They look like little flat-topped mountain peaks. Not at all like a housecat's spinous scales."

"What animal is this second hair from?"

"I've compared it to every animal hair in my database. But this is something I've never seen before."

A mystery creature. Jane thought of Leon Gott's house and its wall of mounted trophy heads. And she thought of his taxidermy workshop where he regularly sc.r.a.ped and dried and stretched the pelts of animals from around the world. "Could this hair be from a snow leopard?" she asked.

"That's pretty specific. Why a snow leopard?"

"Because Gott was working on a snow leopard pelt, and it's now missing."

"They're extremely rare animals, so I don't know where I'd get a hair sample to compare. But there is a way to determine species. Remember how we ID'd that weird hair from the Chinatown murder? The strand that turned out to be from a monkey?"

"You sent it to a lab in Oregon."

"Right, the Wildlife Forensics Lab. They have a database of keratin patterns from species around the world. With electroph.o.r.esis, you can a.n.a.lyze a hair's protein component and match it against known keratin patterns."

"Let's do it. If this hair came from a snow leopard, then it was almost certainly transferred from Gott's house."

"In the meantime," said Erin, "get me that house cat hair. If the DNA matches, you'll have the proof you need that these two murders are linked."

"YOU WERE A BIG MISTAKE," SAID MAURA. "I NEVER SHOULD HAVE brought you home."

The cat ignored her and licked its paw, fastidiously cleaning up after devouring a meal of imported Spanish tuna packed in olive oil. An extravagance at ten dollars a serving, but he'd refused to touch the dry cat food, and Maura had forgotten to pick up more cans of gourmet cat food on her way home that afternoon. A search of her pantry had turned up that one precious can of tuna, which she'd intended to use in a nice salade Nicoise with crisp green beans and red potatoes. But no, her greedy little houseguest lapped up every tasty morsel and sauntered out of the kitchen, making it clear that Maura's services were no longer needed.

So much for companionship. I'm just the maid. Maura rinsed the cat bowl in hot soapy water and placed it in the dishwasher for a thorough, microbe-blasting scrub. Could you catch Toxoplasma gondii from a cat in just a week? Lately she'd been obsessed with toxoplasmosis, because she'd read it could lead to schizophrenia. Crazy cat ladies were crazy because of their cats. This is how these crafty animais control us, she thought. They infect us with a parasite that makes us serve them ten-dollar cans of tuna.

The doorbell rang.

She washed and dried her hands thinking Die, microbes! and walked to the front door.

Jane Rizzoli stood on the porch. "I'm here for the cat hair," she said and pulled tweezers and an evidence bag from her pocket. "You do the honors."

"Why don't you?"

"He's your cat."

With a sigh, Maura took the tweezers and went into the living room, where the cat now sat on the coffee table, staring at her with suspicion in his green eyes. They'd been together for a week and she had not yet bonded with the animal. Was it possible to actually bond with a cat? At the Gott crime scene, he had lavished affection on Maura, mewing and rubbing against her until she'd been seduced into adopting him. Since she'd brought him home, his att.i.tude had been sheer indifference, even though she'd lavished him with tuna and sardines. It was the universal lament of disappointed wives: He charmed me, wooed me, and now I'm his maid.

She knelt down beside the cat, who promptly jumped off the coffee table and strolled toward the kitchen with an att.i.tude of sleek disdain.

"It has to be plucked straight from the animal," said Jane.

"I know, I know." Maura followed the cat down the hallway, muttering: "Why do I feel so ridiculous?"

Maura found the cat sitting where his bowl should be and his eyes fixed on hers with an accusing glare.

"Maybe he's hungry," said Jane.

"I just fed him."

"So feed him again." Jane opened the refrigerator and took out a carton of heavy cream.

"I need that for a recipe," said Maura.

"I need cat hair." Jane poured the cream into a bowl and set it down. The cat instantly started lapping it up. He never even noticed when Jane plucked three hairs from his back. "When all else fails, try bribery," said Jane, sealing the hairs in the evidence bag. "Now I just need to get a sample from that other cat."

"No one's been able to catch the other cat."

"Yeah, that's gonna be a problem. Frost's been to the house every day this week and hasn't even spotted it."

"Are you sure it's still in the house? It hasn't escaped?"

"Something's eating the cat food, and that house has a lot of places to hide. Maybe I can trap him. You got a cardboard box I can use?"

"You'll also need gloves. Do you have any idea how many nasty infections you can get from a cat scratch?" Maura went to the hall closet and found a pair of brown leather gloves. "Try those."

"Gee, these look really expensive. I'll try not to ruin them." She turned toward the front door.

"Hold on. I need a pair. I know I've got some more in here."

"You're coming, too?"

"That cat doesn't want to be caught." Maura reached into a coat pocket and found a second pair of gloves. "This is definitely a two-woman job."