An obvious advantage of having the forensic science labs inside my building was I didn't have to wait for paper reports. Like me, the scientists often knew a lot before they began writing anything down. I had submitted Beryl Madison's trace evidence exactly one week ago. It would probably be several more weeks before the report was on my desk, but Joni Hamm would already have her opinions and private interpretations. Having finished the morning's cases and in a mood to speculate, I keyed myself up to the fourth floor, a cup of coffee in hand.

Joni's "office" was little more than an alcove sandwiched between the trace and drug analysis labs at the end of the hall. When I walked in she was sitting at a black countertop peering into the ocular lens of a stereoscopic microscope, a spiral notebook at her elbow filled with neatly written notes. "A bad time?"

I inquired.

"No worse than any other time," she said, glancing around distractedly.

I pulled up a chair.

Joni was a petite young woman with short black hair and wide, dark eyes. A Ph.D. candidate taking classes at night and the mother of two young children, she always looked tired and a bit harried. But then, most of the lab workers did, and in fact the same was often said of me.

"Checking in on Beryl Madison," I said. "What have you found?"

"More than you bargained for, I have a feeling."

She turned back through pages in the notebook. "Beryl Madison's trace is a nightmare."

I wasn't surprised. I had turned in a multitude of envelopes and evidence buttons. Beryl's body was so bloody it had picked up debris like flypaper. Fibers, in particular, were difficult to examine because they had to be cleaned before Joni could put them under the scope. This required placing each individual fiber inside a container of soapy solution, which in turn was placed inside an ultrasound bath. After blood and dirt were gently agitated free, the solution was strained through sterile filter paper and each fiber was mounted on a glass slide.

Joni was scanning her notes. "If I didn't know better," she went on, "I'd suspect Beryl Madison was murdered somewhere other than her house."

"Not possible," I answered. "She was murdered upstairs, and she hadn't been dead long when the police got there."

"I understand that. We'll start with fibers indigenous to her house. There were three collected from the bloody areas of her knees and palms. They're wool. Two of them dark red, one gold."

"Consistent with the Oriental prayer rug in the upstairs hallway?"

I recalled from the scene photographs.

"Yes," she said. "A very good match with the exemplars brought in by the police. If Beryl Madison were on her hands and knees and on the rug, it would explain the fibers you collected and their location. That's the easy part."

Joni reached for a stack of stiff cardboard slide folders, sorting through them until she found what she was looking for. Opening the flaps, she perused rows of glass slides as she talked. "In addition to those fibers, there were a number of white cotton fibers. They're useless, could have come from anywhere and possibly were transferred from the white sheet covering her body. I also looked at ten other fibers collected from her hair, the bloody areas of her neck and chest, and her fingernail scrapings. Synthetics."

She glanced up at me. "And they aren't consistent with any of the exemplars the police sent in."

"They don't match up with her clothing or bed covers?" I asked.

Joni shook her head and said, "Not at all. They appear foreign to the scene, and because they were adhering to blood or were under her nails, the likelihood is strong they're the result of a passive transfer from the assailant to her."

This was an unexpected reward. When Deputy Chief Fielding finally got hold of me the night of Beryl's murder, I had instructed him to wait for me at the morgue. I got there shortly before one A.M. and we spent the next several hours examining Beryl's body under the laser and collecting every particle and fiber that lit up. I had just assumed most of what we found would prove worthless debris from Beryl's own clothing or house. The idea of finding ten fibers deposited by the assailant was astonishing. In most cases I was lucky to find one unknown fiber and considered myself blessed to find two or three. I frequently had cases where I didn't find any. Fibers are hard to see, even with a lens, and the slightest disturbance of the body or the faintest stirring of air can dislodge them long before the medical examiner arrives at the scene or the body is transported to the morgue.

"What sort of synthetics?" I asked.

"Olefin, acrylic, nylon, polyethylene, and Dynel, with the majority of them being nylon," Joni replied. "The colors vary: red, blue, green, gold, orange. Microscopically they're inconsistent with each other as well."

She began placing one slide after another on the stereoscope's stage and peering through the lens.

She explained, "Logitudinally, some are striated, some aren't. Most of them contain titanium dioxide in a variety of densities, meaning some are a semidull luster, others dull, a few bright. The diameters are all rather coarse, suggestive of carpet-type fibers, but on cross section the shapes vary."

"Ten different origins?"

I asked.

"That's the way it looks at this point," she said. "Definitely atypical. If these fibers were transferred by the assailant, he was carrying an unusual variety of fibers on his person. Obviously, the coarser ones aren't from his clothing because they're carpet-type fibers. And they're not from any of the carpets inside her house. For him to have such a variety is peculiar for another reason. You pick up fibers all day long, but they don't stay with you. You sit somewhere and pick up fibers, and a little later they're brushed off when you sit somewhere else. Or the air dislodges them."

It got more perplexing. Joni turned another page in her notebook and said, "I've also put the vacuumings under the scope, Dr. Scarpetta. The debris Marino vacuumed off the prayer rug, in particular, is a real hodgepodge."

She skimmed a list. "Tobacco ash, pinkish paper particles consistent with the stamp on cigarette packs, glass beads, a couple bits of broken glass consistent with beer bottle and headlight glass. As usual, there are pieces and parts of bugs, vegetable debris, also one spherical metal ball. And a lot of salt."

"As in table salt?"

"That's right," she said. "All this was on her prayer rug?"

I asked. "Also from the area of the floor where her body was found," she replied. "And a lot of the same debris was on her body, in her nail scrapings, and in her hair."

Beryl didn't smoke. There was no reason for tobacco ash or particles from a cigarette pack stamp to be found inside her house. Salt is associated with food, and it didn't make sense for salt to be upstairs or on her body.

"Marino brought in six different vacuurnings, all of them from carpets and areas of the floor where blood was found," Joni said. "In addition, I've looked at the control sample vacuumings taken from areas of her house or carpets where there was no blood or evidence of a struggle -areas where the police think the killer didn't go. The vacuumings are significantly different. The debris I just listed was found only in those areas where the killer was thought to have been, suggesting that most of this material was transferred from him to the scene and her body. It may have been clinging to his shoes, his clothing, his hair. Everywhere he went, everything he brushed up against collected some of this debris."

"He must be a veritable Pig Pen," I said.

"This stuff is almost invisible to the naked eye," the ever-serious Joni reminded me, "He probably wouldn't have a clue he was carrying so much trace on his person."

I studied her handwritten lists. There were only two types of cases from my past experience that might account for such an abundance of debris. One was when a body was dumped in a landfill or some other dirty place such as a road shoulder or gravel parking lot, the other when it was transported from one scene to another in the dirty trunk or on the dirty floor of a car. Neither scenario applied to Beryl.

"Break it down for me by color," I said. "Which of these are likely to be carpet versus garment fibers?"

"The six nylon fibers are red, dark red, blue, green, greenish yellow, and dark green. The greens may actually be black," she added. "Black doesn't look black under the scope. All of these are coarse, consistent with carpet-type fibers, and I'm suspicious some of them may be from vehicle versus household carpeting."

"Why?"

"Because of the debris I found. For example, the glass beads are often associated with reflectorized paint, such as is used in street signs. The metal spheres I find quite often in car vacuumings. They're solder balls from the assembling of the vehicle's undercarriage. You don't see them, but they're there. Bits of broken glass-broken glass is all over the place, especially along road shoulders and in parking lots. You pick it up on the bottom of your shoes and track it into your car. Same goes for the cigarette debris. Finally, we're left with salt, and that makes me most suspicious the origin of Beryl's trace is vehicular. People go to McDonald's. They eat french fries inside their cars. Probably every car in this city has salt in it."

"Let's say you're right," I said. "Let's say these fibers are from car carpeting. That still doesn't explain why there would be possibly six different nylon carpet fibers. It's not likely this guy has six different types of carpet inside his vehicle."

"No, that's not likely," Joni said. "But the fibers could have been transferred to the inside of his car. Maybe he works in a profession that exposes him to carpets. Maybe he has an occupation that puts him in and out of different cars throughout the day."

"A car wash?"

I asked, envisioning Beryl's car. It was spotless inside and out Joni thought about this, her young face intense. "Could very well be something like that. If he works in one of these car washes where attendants clean the interiors, the trunks, he'd be exposed to a variety of carpet fibers all day long. It's inevitable he's going to pick up some of them. Another possibility is he works as a car mechanic."