Panning his flashlight inside the darkened Northeast Washington rowhouse, D.C. police detective Chris MacWilliams examines knee-high heaps of newspapers and magazines on the floor. Some are from the 1970s. He pokes through a stack of unopened bills.

The investigator turns to the kitchen and opens the refrigerator. The shelves are empty. The house lights don't work, and dust floats like snowflakes in the flashlight's beam. Flies, hundreds of them, are buzzing and bouncing off window shades. That's why MacWilliams is here: Neighbors called about the flies.

He creaks up the stairs, and when he reaches the bedroom he finds what he expected: a corpse. The dead man is half-resting on a bare mattress; his skin looks like leather. The detective digs through some drawers and finds ear plugs, ear wax remover and hundreds of cotton swabs. "He was probably hearing voices," MacWilliams surmises.

This is the kind of police investigation that the public rarely hears about and that few inside the force are eager to conduct. Tracking down the bodies of people who die naturally or take their own lives can be emotionally draining, physically uncomfortable, lonely.

"We just drive around the city, and nobody knows who we are," says MacWilliams, a plainclothes officer who travels in an unmarked car. "Some days, I feel like the Grim Reaper."

MacWilliams is one of four detectives on the D.C. police department's natural death squad, a unit that sees more bodies than any other on the 3,800-member force.

Assigned to investigate deaths that are not suspected homicides, the squad handled more than 800 of the city's nearly 4,000 deaths reported to the D.C. medical examiner last year: cases involving strokes, heart attacks, industrial accidents, drownings and suicides.

Disbanded in the mid-1990s, the unit was reestablished two years ago. Police officials hoped it would streamline death investigations and give homicide detectives, who had been handling such cases, more time to work on killings.

MacWilliams and his partners, all former homicide detectives, had grown tired of murder, fatigued by uncooperative witnesses and long hours. The natural death squad promised more regular shifts and more time with their families. Still, they have found that the work is harder than they imagined. They talk about how the stink of death clings to their skin, hair and clothes, how it sometimes lingers in their nostrils for days.

"It's like they don't want you to forget them," says MacWilliams of the departed. "You can't really explain it."

It's like death's film "just latches onto you and won't let go," he says.

Most of the city's deaths occur in hospitals or under a doctor's care and do not require autopsies or investigations. Even homicide detectives can go months without seeing a corpse because, unlike in the television dramas, by the time they arrive at the crime scene, an ambulance crew often has removed the body.

The natural squad is not spared.

They see suicide victims dangling from shower heads and disintegrating bodies whose stench has reached neighbors a block away.

Their work has two purposes: to ensure that the deceased is not a homicide victim and to help pathologists determine a cause of death by gathering as much information as possible. Thus, the job is often a solitary journey through a decedent's home and possessions. Was the deceased a hermit or just terminally sick? Is there a bank statement or letter lying around that will help locate the person's next of kin? What medications was the person taking? How many pills are missing?

Sometimes an entire life -- and death -- unfolds for a natural squad investigator through a few pieces of paper.

At the Northeast rowhouse, MacWilliams finds hospital records that indicate the dead man's father suffered from dementia. Perhaps, the detective says, mental illness runs in the family. MacWilliams opens a bank statement postmarked almost a month earlier. It shows a balance of $1.78.

MacWilliams's mind churns: The man couldn't afford to eat or pay his bills, he suspects, which explains the empty fridge and lack of electricity. Instead of seeking help, the man withdrew behind his drawn shades, amid piles of periodicals. He figures the death was probably caused by starvation or a heart attack. It will almost certainly be ruled a natural death, even if it doesn't feel like one.

MacWilliams walks out the front door into the sunlight.

Who knows when and where the next body will be found?

The Cheap Cigar

Natural squad detective Randy Brooks looks like an actor in a noir-style movie. He wears all black. Black shoes. Black slacks. Black shirt. Black tie. Black fedora. A dark, graying mustache curves around his mouth.

It is 10 p.m. on a Tuesday night, and Brooks has been summoned to a Northeast apartment complex where a 98-year-old woman was found dead in her bedroom.

Walking into the woman's cluttered apartment, he can smell death. He has something he finds particularly helpful on such occasions: cheap cigars, stashed in his jacket pocket and the glove box of his car. He doesn't normally smoke. But the aroma of his Black & Milds masks the putridness of rotting remains.

Brooks, who has been on the force since 1978, is never in a hurry. There is no need to rush and find witnesses or make sure that crime-scene technicians get the right photographs. Standing in the 98-year-old woman's kitchen, he reaches into his pocket and pulls out a cigar. He lights it, the embers casting a glow across his face.

With cigar smoke collecting in a haze at the ceiling, Brooks begins his investigation, taking note of religious figurines on a coffee table. He spots a faded pillow embroidered many years ago. It begins: "To a soldier far away from home."

He is cataloguing the scene with an aim: to rule out a crime. Nothing seems out of place, no sign of a break-in or struggle.

Brooks enters the bedroom and finds the woman slumped at the edge of the bed, facing a large mirror. The detective rummages through the closets and drawers, looking for identification cards. In a purse, he finds a few scraps of paper, with the names and phone numbers of several relatives. One note begins with words that seem meant for Brooks: "If something should happen to me, please call . . ."

Such lonely deaths are the hardest on the detective, who has seen some of the worst that people can inflict on one another. He lives with his own elderly mother in Northwest Washington. After such deaths, he calls her to be sure she's all right. It is too late to call her tonight, so he makes a mental note to check on her in the morning.

Brooks stubs out his Black & Mild and puts it behind his right ear. He pulls out his cellular phone. He is about to begin what he calls the hardest part of his job: notifying the next of kin.

"I'm Detective Brooks with MPD," he says. "I'm sorry, but I have some bad news for you. We're in her apartment, and she has passed away. . . ."

The detective jots down something in his notepad and then explains to the relative that somebody will have to identify a photograph of the woman at the morgue. He ends the call.

"It is tough to do that," Brooks says. "You imagine yourself in their place."

He relights the cigar, puts it back into his mouth and takes a few puffs.

'This Takes a Toll'

On a recent afternoon, natural squad detective Susan Blue looks up at a Capitol Hill rowhouse. She knows a dead man is upstairs in his bedroom. Work crews on the street smelled something bad and called police. An officer arrived, borrowed a key from a neighbor and found the body upstairs.

Blue turns to the officer. He knows what to expect when he reenters the home, so he wraps a T-shirt around his head to block the odor. His jacket is zipped to his Adam's apple. It is 90 degrees outside. Blue asks him to buy her some cigars, and he hustles to his patrol car for the trip to the convenience store. He seems relieved.

Stepping inside the house, Blue surveys the scene. No broken windows or bashed-in doors. No tipped-over furniture. Just country music twanging from a stereo and fans twirling from the ceiling. Wrinkled clothes occupy a chair.

With sweat pouring from her rubber gloves, Blue finds the badly decomposing corpse on the floor of the bedroom. An expensive watch rests untouched on a dresser, and a huge bowl of loose change is covered in dust, both signs that no thief has entered the room.

Blue, whom other detectives call one of the most compassionate and fastidious investigators in the department, will spend the rest of the afternoon calling relatives. But the corpse is too decayed to be identified. She will track down dental records, but they will prove inadequate to make an identification. Technicians will then turn to DNA testing, a time-consuming process that forces authorities to hold the body at the morgue for weeks.

Blue is a single mother with an 11-year-old son. And while she enjoys the unhurried pace of the job and the less-demanding hours, "I'm sure this takes a toll," she says. Her psyche is more fragile now. Because she has seen so many accidental electrocutions, she makes sure her son's radio is nowhere near the bathtub.

Maybe the police psychologist she bumped into at an officer's funeral was right. She told Blue that she'd probably burn out on the death patrol within a year.

Routine and Sympathy

Chris MacWilliams walks toward an apartment building where an 80-year-old woman has been discovered dead. She was not well, having suffered a recent heart attack and stroke.

Inside the apartment, where relatives and friends have gathered, the dead woman's daughter is sitting in a chair, sobbing. MacWilliams, 35, a lean man with spiky hair, a goatee and deep bags under his eyes, crouches next to her.

"My condolences to you and your family for your loss," he begins, in a soothing tone. "I'm here to help get your loved one to her final arrangements. I know this was a traumatic event."

MacWilliams, who joined the force 12 years ago and has been investigating homicides and deaths since 2000, runs quickly through a set of prepared questions. When was the last time the daughter had spoken to her mother? Was she feeling well? Anything out of the ordinary?

The daughter answers in short sentences. She last spoke to her mother two days ago. "Okay," MacWilliams says, his hand reaching out and lingering on the woman's shoulder. "I'm going to go into the bedroom and document the scene, look around for her medications and take some photographs."

From the woman's bedroom, MacWilliams can hear Jon Stewart, the comedian, joking about President Bush. Comedy Central. It's the last station the woman watched.

The detective enters the bedroom and takes photographs of the woman and the scene. He struggles to roll the body over -- it's in terrible shape -- but can't see any obvious signs of trauma. He removes six of eight rings on her fingers, a difficult task because the fingers are swollen. The effort serves no investigative purpose. He just doesn't want the rings to be sawed off at the morgue in order for the family to have them.

Stuffing his rubber gloves into a pocket, he walks into the other room and crouches next to the daughter. He says the body will have to be taken to the medical examiner's office for an autopsy. The woman begins to shake and cry.

MacWilliams leaves the apartment.

"Tomorrow is not promised to anyone," he says. "I know that firsthand."

Members of the D.C. police natural death squad are, from left, detectives Susan Blue, Jed Worrell, Chris MacWilliams and Randy Brooks.

MacWilliams investigates a death in Northeast Washington.

Detective Randy Brooks takes a cell phone call about another case as medical examiner technicians Rashod Holmes, in the van, and Rashid Jones load a body.

Detective Chris MacWilliams, left, and neighborhood residents John Bratton Jr. and Delores Bratton watch as a body is removed from a D.C. rowhouse.

MacWilliams searches the belongings of a Northeast man whose body was found several weeks after he died.

Detective Chris MacWilliams is offered a pair of gloves by Officer Calvin Awkward as they discuss a difficult case involving a badly decomposed body. MacWilliams and his partners are all former homicide detectives.

Detective Randy Brooks makes a phone call to tell a loved one of a death. It might go something like: "I'm sorry, but I have some bad news for you."