In the white-tiled autopsy room early on a Tuesday, six naked bodies lie waiting to relay their last messages.

There is an enormous fat woman and a wizened old man, who both died at home during the night. There is a grizzled alcoholic, his body covered with tattoos.

There is a muscular young man with no wound save a tiny injection site, a hefty fireman who breathed too much smoke and a recluse discovered by neighbors weeks after her death.

As rock music pulses from a radio, Dr. Douglas Dixon moves from table to table, carefully looking over each corpse for news of its final moments of life.

He checks the eyes and neck for signs of strangling, the skin for wounds and surgical scars.

He reads the police report on each death, looking for suspicious circumstances or a history of dangerous illness -- heart disease, cirrhosis, high blood pressure.

If the story, the examination and the medical record all point to natural death, the case will be closed. If doubt remains, the body will be autopsied, as was done about 1,000 times last year.

A third of the people who die in the District of Columbia each year are brought to the medical examiner's office for what the chief medical examiner, Dr. James L. Luke, calls their last chance to speak.

For these dead -- some of them victims of violence, drugs or alcohol, others of natural disease and lack of medical care -- Washington's "Quincys" must render a medical verdict crucial to the victims' families and the community.

They must determine the cause and manner of death -- information that serves the city's justice system, helps monitor its health care and touches its citizens in countless ways.

"They're real people," Luke said. "They aren't just dead bodies. Our job isn't just to see how many of them there are. It's to find out what happened . . . and who is this person."

Luke maintains that the television series "Quincy" overplays the drama of the job, but he and his deputy, Dr. Brian Blackbourne, have had their share of cases in which the autopsy, their chief duty, provided the clue that explained a baffling death.

There was the young marine biologist who had just moved into McLean Gardens in Northwest Washington. One day she didn't show up to go swimming with a friend and was found dead in her apartment with a piece of sheet tied around her neck and a curtain rod lying on the floor.

At first glance it looked like a hanging, but according to Luke, several things made that unlikely. Her neck was not severely injured, her wallet was missing and there were signs she had been raped. Her father said she had not been depressed. "I signed the case out as violent asphyxial death [strangulation]," Luke recalled, "and a maintenance man in the building was finally accused and convicted."

There was the baby in the swing. As Blackbourne tells it, a baby sitter left in charge of an infant called the mother at her office one day, saying that she couldn't wake up the child. When the mother asked what had happened, the sitter said, "The baby fell out of the swing."

According to Blackbourne, the baby was rushed to the hospital in a coma, eventually was transferred to another hospital and died five days later. All the medical records read, "Baby fell from swing." When Luke autopsied the child, he found an eight-inch skull fracture. He called a detective in Prince George's County, where the child lived, and told him to go out and get the swing.

When the detective brought the swing to the medical examiner's office, Luke and Blackbourne knew at once that the story was a lie. The swing was small and portable, with a secure canvas seat only two feet off the floor. "We told him we just didn't buy it," Blackbourne said.

The detective returned to the station, checked the baby sitter's record and discovered she had been found "not guilty by reason of insanity" in the death of another child a few months earlier. She later was arrested and convicted of second-degree murder.

In these and other, less dramatic ways, the city's five medical examiners -- forensic pathologists, or specialists in unnatural death -- work at their three-story building on the grounds of D.C. General Hospital to find out what happened to people. Besides performing the autopsies -- external and internal examinations done to document diseases, injuries and causes of death -- they and their technicians collect samples of blood, urine, stomach contents and tissue from various organs that are tested by toxicologists for the presence of alcohol, heroin and more than 300 other drugs.

They travel to the scene of death to examine homicide, suicide and accident victims, testify in court when cases come to trial, and meet with lawyers, family members, consumer safety advocates and others with legitimate interest in a case. The findings they record year after year create a unique, ongoing chronicle of death in the city.

To do the job, according to Luke, they must find out as much as possible about each victim. "We have to be prepared not only to give the cause of death," he said, "but to know the answers to questions like, 'When did he last eat?' 'How do you know it's a battered child?' 'How drunk was she?' 'Was he a drug addict?' 'What is the caliber of the gunshot wound?'"

The answers are not important only to the courts. The medical examiners believe they have a responsibility to speak out on unsale products and warn other doctors and the public about preventable health hazards. Blackbourne, for example, has worked for several years to strengthen safety standards on automobiles, cribs and other products, and Luke has done research on sudden infant death syndrome and the role of alcohol in accidents and violent crimes.

Although the most glamorous part of the job is gathering medical evidence in homicides, many other kinds of death come under the medical examiners' charge. Each year, the office investigates more than 3,000 deaths that occur in the District, including all homicides; suicides; deaths from injury, accident or drugs; deaths of prisoners and of patients hospitalized for less than 24 hours. It also examines all those who die at home or unexpectedly, and those who have had no regular medical care.

Eighty percent of all deaths investigated are attributed to natural causes.But of the ones chosen for a full autopsy -- 1,060 last year -- natural disease accounts for only 40 percent. Homicide, suicide and accidents make up most of the rest. In about 7 percnet of cases autopsied, the cause of death may be evident -- for instance, drowning or an overdose of drugs -- but the tests do not show whether it was homicide, suicide or accident.

Usually the results are more conclusive. Blackbourne recalls, for example, the case of the taxi driver who hit a tree. He was brought to the office as a traffic fatality, but no one understood initially why he had been killed when the tire tracks indicated he had only been going 15 miles an hour. Nor could they see why the rear window of the car had shattered when it was the front end that had struck the tree.

"We were cleaning him off to take an ID photo and one of our techs said, 'Uh oh,'" Blackbourne said. On the man's cheek was a gunshot wound and another in his back. That explained the accident, the death and the window.

Then there was the young man who awoke in the middle of the night in what Blackbourne described as "a state of white panic." He told his girlfriend he needed a drink, quaffed a vodka and soda, then ran out of the apartment naked. She pursued him and got him into his car, where he had a violent seizure that was still going on when she arrived with him at an emergency room. Despite the efforts of the doctors, his seizure continued and he died of sudden, rapid failure of the heart and circulatory system.

"At autopsy, he had 10 packets of cocaine in his stomach wrapped in six layers of condom," Blackbourne said. The man had left Columbia two days earlier and had smuggled the cocaine into the United States. But he had made the packets so large that they could not pass out of the stomach into the intestines. Digestive acid had finally eaten through the rubber wrapping of one packet. "Three grams of 68 percent pure cocaine was dumped in his stomach," said Blackbourne, causing the excitement, seizures and collapse.

And there was the beer drinker who passed out one night in his favorite bar and grill. Since he was a steady customer who regularly had too much to drink with dinner, the waiters let him sleep at his table for a while. But at last they worried about his presence disturbing other customers. So, according to Blackbourne, "They picked him up and helped him out the back door and sat him down in the alley." Hours later he was still sitting there -- dead. At autopsy, the medical examiner found a piece of meat in his windpipe, and determined that he had quietly choked to death in plain sight of everyone.

Such surprises add spice to the medical examiners' jobs, but even their routine cases offer an engrossing view of city life. On one typical morning, Luke, Blackbourne and Dr. Edward Zimney were each performing autopsies at side-by-side tables, assisted by technicians and watched by two medical students from George Washington University.

On Luke's table lay a young woman who had died after being in a coma for a month at a local hospital. She had originally come to the emergency room with severe back pain, and doctors had suspected a ruptured disc. But tests revealed nothing, so they concluded the pain was caused by muscle spasms and anxiety. When given one dose of a tranquilizer, she suffered a severe, rare reaction that sent her body temperature soaring to 109 degrees. By the time she could be cooled down, the heat had irreparably damaged her brain, kidneys and other organs.

Luke made a large, Y-shaped surgical incision in the woman's chest and abdomen, and gently peeled back the layer of skin and muscle as if he were opening a coat. He examined the muscles, and excitedly called the other doctors over. "Look at that!" he exclaimed. "I've never seen anything like it."

Sharply defined patches of normally red muscle had turned greenish-brown -- a sign of dead tissue, killed by the severe fever.

At the next table, Zimney, the youngest of the office's five pathologists, was performing an autopsy on a large woman -- a former mental patient suffering from schizophrenia -- who had committed suicide by jumping off the Calvert Street Bridge.

And on Blackbourne's table lay a young man who had been found dead in a doorway with a gunshot wound in the head. As the pathologist was diagramming the location of the wound and jotting down other findings -- "needle tracks" on the forearms from heroin injections and a scrape on one cheek -- a clerk at the front desk called the autopsy room to announce that the man's relatives had arrived to identify the body.

Blackbourne went upstairs to meet them, accompanied by a technician -- a rule observed ever since a relative of one victim, furious with grief, punched Blackbourne in the mouth upon seeing the body. Blackbourne introduced himself and explained the procedure: rather than seeing the corpse, they would see an image of the man's face on a closed-circuit television. Luke introduced the system several years ago because he felt it was more humane than confronting family members with a body, although if they cannot make a positive identification from the screen they are ushered downstairs for a side view through a window.

Blackbourne accompanied the two men into the identification room and flipped on the television. A camera downstairs was already focused on the shooting victim, and his serene face flickered into view, showing no evidence of the bullet wound in the back of his head.

The pair gazed impassively at the image. "It's him," said one. "No question."

Although the medical examiner is most often called as a witness for the prosecution in murder cases, Blackbourne said the agency is impartial, and its information may help acquit defendants as well as convict them.

"We just gather the facts and record them," he said. "Those same facts may be consistent with many different things. A contact gunshot wound to the temple can be a suicide or an armed robbery."

To gather the facts, a medical examiner can be called by detectives at any time of day or night to view a body before it is moved. On one recent afternoon, Zimney was summoned to an apartment in Northwest Washington to help in a homicide investigation.

The victim, a middle-aged man, had been discovered dead in his apartment by a janitor a few hours earlier. He had been stabbed several times, and there were bloodstains on the walls and carpet. While police dusted for fingerprints, Zimney examined the wounds, photographed the body and set about estimating the time of death.

He felt the temperature of the skin, then moved the arms and legs to check for rigor mortis. Rigor mortis -- muscle stiffness that sets in two or four hours after death and lasts for about a day -- is still considered the most accurate clue to the time of death, although its time of onset and disappearance can vary depending upon the dead person's size and the surrounding temperature.

The man's limbs were slightly stiff, but could be bent easily at the knees and elbows. From that finding and other clues, Zimney estimated that he had been dead longer than two days. Plastic bags were taped over the hands to preserve any hairs or fibers that might be used as evidence, and the body was taken to the medical examiner's office for a more thorough examination and the final report on the cause of death.

The District's medical examiner system, in which all autopsies are done by forensic pathologists, was established by law in 1971. It replaced the coroner system, in which coroners did not have to have special training, and gave the medical examiner authority to perform all tests necessary to find the cause of death in any case under his or her jurisdiction.

Besides the District, only about 13 states -- including Maryland and Virginia -- have centralized systems in which all autopsies are conducted by forensic pathologists, according to Dr. William Eckert, president of the National Association of Medical Examiners. He said most major cities have medical examiners, but in many areas, coroners are still elected locally and are not always required to be doctors.

In Maryland, bodies to be autopsied are shipped to the medical examiner's office in Baltimore, but local deputies -- doctors appointed by a state commission -- investigate deaths in each county and decide whether an autopsy is needed, according to Dr. Russell Fisher, the state medical examiner.

In Virginia, doctors appointed by local medical societies examine bodies at the scene of death and decide whether an autopsy is required, according to Dr. David Wiecking, the state medical examiner. Autopsies are done either in Richmond or by a forensic pathologist in one of the regional offices in Fairfax, Norfolk or Roanoke.

In both states, local deputies are paid by the case, and Fisher and Wiecking said they have trouble finding enough doctors willing to take the responsibility, "It's a dog's job getting up in the middle of the night and spending two or three hours for a lousy 50 bucks," Fisher said.

In the 10 years since Luke became the District's first chief medical examiner, he has transformed the office from a morgue staffed by nonspecialists to one with top-flight facilities and a national reputation for excellence.

"This city has no idea how lucky it is to have this operation," said Truman A. Morrison, an associate judge of the District's Superior Court and former head of the trial division of the D.C. public defenders. "Most people don't have any idea that it exists."

Luke's staff of 37 doctors, technicians, toxicologists and secretaries is smaller by one position than it was 10 years ago, and his budget -- about $1.1 million for this fiscal year -- has lost ground to inflation. But despite the grisly nature of the job, morale has remained high and turnover low.

It does bother some of the staff that people misunderstand what they do, or assume they are hardened because they work with the dead. "Even your families might think you kind of lose touch with a sympathetic feeling," said Yvonne Williams, who was hired three years ago as the first woman autopsy technician."No matter what the situation is, [they think] you should stand strong and be able to handle it. I have to keep in touch to make sure I don't deny myself the tears. . . . I'm affected the same way they are."