A hundred yards below a private cemetery where generals have gathered for a military funeral, ghostly figures in white protective suits are digging up a clandestine grave next to a fetid river.

It is painstaking labor in a land littered with secret graves. This is the 30th excavation this year for criminologist Israel Ticas, who leads the teams that search for bodies still missing from a decades-old civil war, and for those killed more recently by street gangs who hold most of El Salvador in their clutches.

The remains often are unidentified, but this time Ticas knows he is looking for members of the Mara Salvatrucha gang who were snatched from a bus station days before. In an unusual break, police captured three of the rival 18th Street gangsters and chased others into the arroyo with the fresh graves.

Ticas is working against the clock. By law, the government has 72 hours to collect the corpses and produce evidence of murder, or else the suspects will be released. But it is slow going, as the bodies have been beheaded and dismembered, and though they are not long dead, worms have begun to feed on them.

The air is thick with the smell of human decomposition, and perhaps with fear. Police stand guard against gangsters who would stop the search if they could. When shots ring out suddenly, panic grips the crew before they realize that the gunfire comes from an honor guard at the military funeral overhead.

Ticas is up to his armpits in dirt, as he sometimes is several days a week. Hour after hour, he moves bits of earth with an archeologist's precision, his face streaked with sweat and soil. Late in the day, with October skies threatening rain, he urges two assistants to make haste, but not to repeat the errors of the previous evening. In darkness, he says, a crew from the morgue took away a torso but forgot the head.

"This is not just an exhumation. It is a crime scene," he reminds them. They are working for the attorney general, who must have bodies to make a case for murder.

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Some would argue that digging up graves is a fool's errand in El Salvador, a country with the world's second highest per capita homicide rate after neighboring Honduras. But this is a vocation for Ticas, who calls himself the "lawyer for the dead." In fact, he is a systems engineer turned police detective who taught himself forensic science. Most address him by his academic title, "Engineer."

Short and solidly built, he looks younger than his 51 years. Ticas speaks in the street slang of the gangsters who occupy his neighborhood, but looks the part of a plainclothes cop. When not in biohazard gear, he wears a leather jacket and dark glasses, or a double-breasted suit with a tie held in place by a gold clip.

He was a young police intelligence agent during the US-backed government's war against Farabundo Marti National Liberation Front guerrillas in the 1980s. Today, those former guerrillas hold the presidency, and Ticas works for an independently named attorney general as the department's only criminologist.

Ticas knows the risks of his work better than anyone. He sees the evidence of gang rape and sadistic methods of murder such as crushed skulls or "the pinata," in which a victim is hung upside down from a tree and hacked to death with machetes, like children batting a candy-filled pinata.

He considers all killers to be devils, no matter their affiliation. He calls himself a lawyer because he seeks justice for the dead, whoever they might be and whoever may have killed them. It so happens that gangs are doing the lion's share of killing to enforce their control, and going to great lengths to conceal the dead, many of them women and discarded girlfriends.

He calculates that in the last 12 years he has opened about 90 common graves with more than 700 bodies, about 60 percent of them women and girls. That is a fraction of what's out there, he believes, but Ticas does not have the time or staff to find all of them.

Body counts also serve as political ammunition. In 2012 and 2013, El Salvador's previous leftist government helped negotiate a truce between the gangs, during which time it claimed that homicides fell by 60 percent. But detractors, including Ticas's boss, Attorney General Luis Martinez, saw the truce as government collusion with criminals. They argue that the dead simply were dumped in clandestine graves by the country's tens of thousands of gang members.

Ticas insists he does not want to play this political tug of war. Rather, he is a technician serving the rule of law from a small office that looks like a museum of horrors, with models of skulls and limbs, and walls papered in photographs of severed heads and salvaged bodies.

From his desk, Ticas pulls out a dozen dog-eared catalogues of violence, one for each year he has worked. They are filled with hand-written notes and color drawings that record how many bodies per grave, their locations, positions, conditions and measurements.

The books provide a meticulous accounting of the extent of the killing across El Salvador, which is why he guards them jealously.

In many cases, he interviews protected witnesses who provide details of murder: "She was killed because she knew too much about gang movements and security houses," according to one account. "A 14-year-old girl was impregnated by a gang member... They did the 'pinata' to her," says another.

The number of missing in El Salvador is a subject of debate, with estimates ranging from 600 to 2,000 per year. Many of those reported missing may well have fled to the United States, while the disappearance of many other Salvadorans goes unreported out of fear of the gangs.

But that doesn't mean families aren't looking. Ticas pulls a metal box out of his desk stuffed with photographs, identity documents and letters from desperate mothers who come knocking on his door at all hours of day and night.

"'Is this where Israel Ticas lives, the one who looks for the dead?' they ask. 'Look, they disappeared my daughter and I need to find her even if she's dead,'" Ticas recounts.

And then he adds without affect, "I get scared because I realize the whole world knows where I live."

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Ticas is passionate about his craft and never misses an opportunity to teach it to assistants, or even to the police guards next to them. The gangs are good at covering their tracks, he says, so you have to locate graves by "tattoos on the land" — broken plant roots and loosely packed soil. Bodies in decomposition swell at first, slackening the earth. Then they begin to breakdown and the ground sinks.

"Look how the color of the soil changes when there is a burial," he says near one grave. A few feet away he pokes a stick into another suspicious area then shakes his head. "There's nothing here."

Ticas started in the field by making drawings of the dead and models of crime scenes. He studied forensic science on his own and in 2002, convinced the attorney general to give him an office and authority for excavating clandestine cemeteries.

In reality, he is still a detective trying to extract information from the dead where many of the living are too afraid to talk. "We have to learn to observe what the silence of the dead is telling us," he says.

One of his innovations, he says, is to dig parallel to the graves rather than on top of them. His team digs deep, L-shaped trenches around the bodies, leaving them on a kind of earthen plinth. In this way, the crew avoids disturbing evidence and can be sure not to jar the bodies from where they fell.

Early on this day, they unearth one body, its head, legs and arms separated from the trunk, and cover it with black plastic. They can see it is a male adolescent and Ticas notes that "those who knew him in life still will be able to identify him."

Then they discover another head, and uncover it bit by bit with a paintbrush until they can observe the manner and angle at which it was separated. The cut is consistent with a machete, they say. Ticas makes notes, and a form is filled out before it is sent to the morgue.

The work takes a psychic toll, Ticas admits. His chatter is rapid-fire. He sometimes clowns around with skeletons, and even once had a birthday cake graveside. He cracks dark jokes that he calls his "comic shield" against the witnessed horrors that keep him awake at night. Yet, he is offended at any suggestion that his humor shows disrespect for the dead.

"When someone has dug up a thousand bodies, then he can talk to me about respect for the dead," Ticas says.

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The Mara Salvatrucha and 18th Street gangs were created by Salvadoran and Mexican immigrants to the United States and were exported back home after the war, then spread like a deadly virus. Here, they fight each other in an unending war for territory and the drug market. They extort businesses and households, rape and murder randomly.

Sometimes their violence is fueled by drugs but more often, gang experts say, it is fed by a hunger for power. They use terror to dominate the general population, and also to control their own; forcing members to participate in the killing ensures their loyalty.

Scarcely a neighborhood is beyond the gangs' reach, and few Salvadorans have been spared this all-pervasive violence. Ticas is no exception.

On his way home during Easter Week a couple of years ago, he got off of a bus alongside a young woman he didn't know and they were surrounded by gangsters. Two of them held him down with a 9 mm pistol in either side of his chest while others hauled the woman off to a nearby field and raped her.

For two hours, he wondered whether she was the target of the attack or he was, or if it was just an average assault. Would they be allowed to live, or would they die and join the disappeared?

"Do you have children?" he finally asked his captors.

"What's it to you?" they answered.

"I have two. Think of your mothers and how they would suffer if you were killed."

Perhaps that is what saved them that day, or perhaps the gangsters just weren't in the mood to kill. He'll never know why he didn't end up in a grave like the three he has just found next to the Metalpa River, in the San Jacinto neighborhood of the capital.

Ticas finishes this job on a Friday afternoon and rushes to his office to file a report to the attorney general. His work is done. He is not there when three 18th Street gang members are released from jail, then rearrested by plainclothes police just outside the door and charged with murder based on the evidence he unearthed.

He does not know how the Mara Salvatrucha gang reacts when they find out the bodies of three of their members have been recovered, or what they may be planning to do in revenge.

Ticas does, however, believe that the gangs want him to keep digging. That's what they tell him, anyway.

"Sometimes the gangsters come up to me and congratulate me and say, 'Engineer, when they kill me, you find all of my body and deliver it to my mother."