Had this been a “normal” multi-fatality fire-say, an out-of-control grease fire in a crowded bar or social club-investigators would already be facing a challenging and intricate death investigation as they sought to assemble each set of remains and give it a name. But this was no ordinary fire-it had been set, deliberately, in the midst of a controversial law enforcement effort that had drawn an enormous amount of media coverage. So the team at Fort Worth would also be conducting a very visible criminal investigation, treating each scrap of bone and shred of tissue as pieces of evidence. The anthropologists permitted at the scene would need to know more than academic science-they'd also have to know how to observe confidentiality mandates and chain-of-custody protocols. In Knoxville, we spelled that mixture of anthropological and forensic expertise “B-A-S-S.”

But Dr. Bass's wife had just died of cancer, and he was in the throes of settling her affairs. Reluctantly, he decided to stay in Knoxville, sending graduate students to go in his place. To our mingled pride, excitement, and apprehension, he chose Bill Grant, Theresa Woltanski- and me.

The three of us piled into my vintage Jeep Cherokee, throwing an odd assortment of clothes, food, and field gear into the back. If we were assigned to the morgue-analyzing the remains as they came in-we'd be issued the normal protective gear: scrubs, gloves, and masks. But if we were assigned to recover remains at the site itself, we'd need to supply our own clothes: work boots, hats, foul-weather gear, and specialized excavation tools. We were taking no chances on showing up unprepared.

We drove all night and showed up in Fort Worth at six a.m.-just one hour before we'd been asked to meet Chief Medical Examiner Dr. Nazim Peerwani in his office. We knew from experience that we wouldn't be allowed to just walk in. A medical examiner's office is almost always secreted behind locked doors and security checkpoints, with carefully controlled access to the public. After all, behind those locked doors, the M.E.'s staff is trying to piece together the stories of the most personal and violent crimes. Distraught families, often ready to lash out at any target, tend to show up at the M.E.'s office, and sometimes perpetrators show up there too, perhaps driven by some irrational urge to further punish their dead victims, hoping to destroy key evidence of their crime, or even seeking to preserve their freedom by killing or disabling one of the scientific sleuths working on their case.

In a mass-fatality incident, with dozens of family members showing up to identify the dead, it's even more important to control access to the morgue. Medical examiners, hoping to shield families from the horrors of a charred body or disfigured face, want very much to control civilians' access to the remains, even as family members insist on seeing their loved ones one last time. Influenced by TV images, many civilians imagine a morgue as a kind of clinical funeral home, with neat rows of peacefully sleeping corpses-as opposed to the blood-spattered and often chaotic place of business that it is.

It's also important to keep out the thrill-seekers who inevitably congregate at disaster sites, their morbid curiosity fueled by the media and occasionally evolving into a fanatical desire to penetrate behind closed doors. Ordinarily rational, well-mannered people suddenly start behaving like spectators at a Roman circus, insisting on their very own up-close-and-personal view of the dead bodies as they appear on TV.

So although Bill, Theresa, and I had not yet worked a mass fatality, we weren't surprised when the large, polite man from the county sheriff's department stopped us as soon as we stepped off the sidewalk.

“Dr. Peerwani is expecting us! Please let us through!” Theresa said impatiently. One of my closest friends in the program, she was always quick to confront any perceived injustice. Now her long blond hair whipped across her sleep-deprived face as she spoke urgently to the officer.

“At least call Dr. Peerwani on your radio,” Bill suggested. A tall, easygoing military veteran who seldom got worked up over anything, he was my other close buddy and, as it happened, Theresa's boyfriend. I looked at him gratefully, glad for his diplomatic skills and his air of quiet authority.

Eventually, we were taken to a reception area where we were issued special identification badges printed right then and there-good for this incident only. Anyone who wanted access to the morgue had to wear one of these highly visible badges at all times.

“Hold on there, folks,” the receptionist said as we headed for the next locked door. “Y'all will have to wait for Dr. Peerwani. He wants to give you the guided tour.”

“Oh, come on!” I said under my breath. After all, we'd been driving all night and we were eager to get started. Later, though, I'd come to appreciate Dr. Peerwani's caution. He knew that once we stepped into his lab, we'd be expected to jump in immediately and assist with the autopsies, and he wanted us to have at least a brief orientation before the relentless work began. Besides, this was his “shop,” and we were here at his request. We needed to learn how things were done on his watch-and he wanted our absorption into his team to be as smooth as possible.

We had seen Dr. Peerwani on television almost every day, so when the darkly handsome Middle Eastern man in his starched white lab coat came through the door, we all stood in an instinctive gesture of respect. The doctor nodded and smiled but never broke stride as he signaled us to follow him into the inner sanctum of the morgue.

We hurried to keep up as Dr. Peerwani took us through the building, barely pausing to toss out a few brief words of introduction to the key people we'd be working with. As he identified various areas of the morgue, I tried to memorize every one of his quick, soft words, which held only a trace of a British-influenced accent. The building was like a maze and I worried that I'd never be able to find my way. But gradually a pattern started to emerge.

First came the “office areas,” the ones where paperwork and research were done. At this early hour, workers were just beginning to fill these halls, turning on lights and opening doors in the staff's personal offices, library, and conference room. Here I saw furniture worthy of a well-heeled law firm, along with lush carpeting, large windows, and soft lighting fixtures. I even heard classical music seeping from under one closed office door. Office workers wore the standard professional suits and dresses.

Then, as we traveled deeper into the inner sanctum, the atmosphere changed along with the decor, as if we were following a photographer's gray scale from light to dark. Suddenly the big windows were gone, the carpet changed to tile flooring, and the institutional fluorescent lights hummed and flickered. Now we were in the lab, where forensics experts were just clocking in, busily covering their T-shirts and blue jeans with white lab coats. These people were getting ready to receive the vials of blood, tissue samples, and bits of trace evidence that would be taken from the bodies waiting for us downstairs, in the autopsy suite.

As we rushed downstairs, the uniform changed once again-the autopsy workers all wore light-blue surgical scrubs. Suddenly Dr. Peerwani stopped in mid-stride and we skidded to a halt, stacking up behind him. He turned and glanced at the three of us, then set off in another direction.

“Go change into scrubs before we go any farther,” he said, nodding in the direction of two well-marked bathrooms. Theresa and I found ourselves in a large room that looked like a health club locker room-large lockers lining one wall, shower stalls and toilet cubicles in the back. Tall shelves stacked with light-blue surgical scrubs in several sizes stood right inside the door. We quickly took off our jeans and T-shirts and slipped on the scrubs over our underwear. Back in the hall, we now resembled the other workers we encountered as we continued our tour, except that these other people wore turtlenecks, thermal underwear, and heavy socks under their gear. And for good reason: As we got closer and closer to the autopsy suite, the air got colder-and the smell got stronger.