Enter the examination room in San Salvador’s Instituto de Medicina Legal, where a masked doctor cuts into a new corpse. The ammonia fumes burn your eyes. After determining the cause of death, he’ll slide the body back into the freezer until someone comes to identify the remains. If no one comes, which sometimes happens—it’s too far, or the family doesn’t have the money, or the deceased doesn’t have a family, or the circumstances of the murder are such that it’s best for the next of kin to lie low—the body will be incinerated. But any corpse in San Salvador that has gone undiscovered long enough, decomposing in a cornfield, say, or cast into the dump, is taken to the Department of Forensic Anthropology.

In contrast to the courtyard, the anthropology room is antiseptic, all right angles and order. Metal examination tables gleam; file boxes are stacked atop the counters and tables and floor. Like puzzle masters, the forensic anthropologists turn over the contents of each and fit the pieces together to figure how a human being turned into a box of bones.

Some of the skeletons are old and weather worn, turning the color of rust; they look as though they would flake at a touch. These bones were exhumed from the site of the 1981 massacre of El Mozote during El Salvador’s civil war, when government troops stormed a suspected guerrilla haven and slaughtered more than nine hundred men, women, and children. Some they killed with guns and machetes; others they corralled into the town church, then set it on fire. This skeleton here, laid out on the butcher paper, strewn with bits of the El Mozote soil mixed with the dust of his own bones, was a man “in his thirties,” one anthropologist estimated. “A farmer, most likely.”

The bones on the neighboring table, sturdier and whiter and in far fewer pieces, are from a newer war, a war more elusive and harder to track: the gang war.

“This one here came from a clandestine grave in San Salvador.” A pit behind a San Salvador slum. She’d been a young woman—they estimated about seventeen, killed within the last year. Based on markings inside her pelvis, she’d once given birth. In the front of the skull, just above where the girl might have tweezed her brows or dusted a shimmer of shadow, was a splintered hole.

“A heavy object,” the anthropologist says, running her fingers along the breach.

“Last week a man came in with thirty-seven bullets,” recalled a morgue administrator. “Thirty-seven! Can you imagine?”

They cut a neat rectangle out of the young mother’s femur for DNA.

It’s hard to know who the particular killers in this new war are. Most homicides—especially the mass graves, like the one from which the young mother was pulled—are known to be the work of the gangs. Yet around 95 percent of crimes in the Northern Triangle go uncharged. To report a mass grave or denounce a gang member for murder carries a near-certain death sentence for the accuser and often for his or her family, too. So people keep quiet; the bodies pile up.

At the front gate of the morgue, a woman is quietly crying, shoulders quaking as she presses a tissue beneath an eye. She leans into a young man, her son perhaps, who wears a stiff expression behind aviator sunglasses. The armed guards notice, then look away.

A different woman enters the gate. “I’m here to register a disappeared?” she says, like a question. She signs her name in the tattered logbook, and the guard points where to go with one hand, holding his gun with the other.

If your local police haven’t found the person you’re looking for, you go to the morgue to make another report. The Instituto de Medicina Legal staff affixes the photograph to a wall, along with dozens of others. They hang beneath a plastic cover so clean it reflects the onlooker, a flickering superimposition against the black and white faces of adults and children arranged by date last seen. THESE PHOTOGRAPHS WILL BE KEPT ON THIS BILLBOARD FOR TWO MONTHS, DEPENDING ON SPACE, the sign explains. It is late July; April’s disappeared have just been taken down.

THANK YOU FOR YOUR ATTENTION, the sign concludes.

A police truck pulls into the compound, and two officers, clad in boots and balaclavas, hop out and escort a scowling young man, no more than sixteen or seventeen. He is handcuffed, his hair is gelled into spikes, and he sports low-sagging shorts, barely laced high-top sneakers, and a bright red T-shirt. The police move him roughly toward one of the doors.

“A gangster,” someone says after he passes.

“They get a psychological evaluation here,” the guard explains, “before going to jail.”

The courts are so backed up that this young man could be in jail for weeks, months, even years before a trial. Thus he, too, becomes one of San Salvador’s missing.