This story is over 5 years old.

The Forensic Dentist Who's Reviving Mexico's Unidentified Corpses (NSFW)

Watch our doc on life, death, and an unassuming Mexican dentist whose proprietary chemical formula rehydrates corpses to lifelike states for identification.
August 18, 2014, 7:00pm

CIUDAD JUAREZ - The man cuts a striking profile. He's been dead for two years—a nameless hit-and-run victim, I'm told, left to bleed out on the side of some dusty road in this Mexico-US border town of 1.5 million people. The accident punched a hole in his forehead. From where I'm standing, hunched over an autopsy stretcher on which his body is strewn akimbo, I can see through to his pickled brain.

If I didn't know any better, there's still life in this man.


It's been 120 hours since Dr. Alejandro Hernández Cárdenas got to work. That's when Hernández Cárdenas, an unassuming local dentist who splits his time practicing, teaching graduate forensic odontology courses at the Universidad Autónoma de Ciudad Juárez, and identifying the unidentified at the Juarez Forensic Science Lab, submerged this man's gnarled, sun-scorched body into what Hernández Cárdenas affectionately calls the "Jacuzzi."

The translucent bathtub-sized tank holds about 60 gallons' worth of an unknown chemical formula—Hernández Cárdenas' secret sauce—that rehydrates corpses for identification. We've tracked this hit-and-run victim, an older man whose corpse Hernández Cárdenas handpicked from one of Juarez's municipal body refrigerators, over the course of a working week as it's soaked in the Jacuzzi.

Along the way, the doctor and his team have catalogued any and all identifying features, such as scars, moles, tattoos, and wounds, that came back into focus through Hernández Cárdenas' method, and are now prepping the victim's revivified hands for fingerprinting.

Based on those fingerprints, together with compounding evidence from any features unique to him that have been restored thanks to Hernández Cárdenas' process, we hope to have an idea of who this man was. At least that's the idea.

These jugs of tri-distilled water were the only ingredient in his solution Hernández Cárdenas allowed us to film. Image: Brian Anderson/MOTHERBOARD

It's a forensic leap that stands to reshape criminal science as we know it. The idea, in short, is to briefly turn back time, flipping your body from a shrunken mummy to something much closer to a freshly-deceased sack of flesh and bone.


When you die, your body goes through seven stages of decomposition. Hernández Cárdenas' proprietary technique allegedly reverses two of these stages, effectively restoring a corpse to its lifelike state. There's stage five, or putrefaction, when the proteins within your body break down to the point that your tissues and muscles rot. And then there's stage six, or proper decomposition, when any lingering water in your body dries up. In the arid, wind-swept desert terrain in and around Juarez, this mortal one-two punch rapidly turns your still-warm corpse into a mummy.

That's where Hernández Cárdenas' patent-pending technique comes in. As he tells us, a thorough soak in his brew can reveal a corpse's true identity, and even cause of death.

He's spent the past two decades working out the kinks, beginning with fingers, then ears, hands, arms, heads, and in one case an entire suit of skin, until one day the local criminal prosecutor's office asked him why not try the technique on a full corpse?

That was 2008. Hernández Cárdenas is now a minor celebrity in the world of criminal science. He's done hundreds of partial-body rehydrations, and to date has performed around a dozen cadaver-sized soaks in the Jacuzzi. He's laying the relatively low-tech infrastructure to one day scale up his technique, he hopes, in pursuit of solving crimes and identifying the unidentified far beyond just Mexico, charging US$60 for the chemicals to pull off a full-body submersion.


"What goes into your solution?" I asked.

"Agua," he smirks.


No one quite knows what goes into it, or exactly how it works. Hernández Cárdenas is careful to not divulge specifics about his Frankensteinian trick. If his patent request is approved, he stands to become the father of a new era of forensics and also make a bit of money. For all we know, his solution really is just water.

That said, he's not alone in this game. In 2005, American forensic researchers at the University of Southern Mississippi secured a patent for a similar rehydration technique, albeit for securing prints from rehydrated fingertips.

That's part and parcel of the sort of small-scale rehydration work being carried out at the Pima County Medical Examiner's Office in Tucson, Arizona, some four hours west of Juarez. This is arguably the hotbed of cases involving unidentified persons found dead in the sand on the American side of the border—since 2001, upwards of 2,000 people have died trying to enter Arizona by way of the vast Sonoran Desert, as The New York Times reports—and finds the PCOME in the unique position of having pioneered a revolutionary rehydration technique for fingertip ridge enhancement.

The PCOME technique, as it's called, uses sodium hydroxide, a highly caustic inorganic compound widely known as lye. It's a delicate dance, according to Dr. Bruce Anderson, a forensic anthropologist with the medical examiner's office, which has been fine-tuning its groundbreaking technique for at least the past decade. Sodium hydroxide will plump up a finger or hand to a certain point, before dissolving it away entirely. Let that finger or hand soak for too long in sodium hydroxide, and the evidence will simply disappear.


This is the risk you run. You have to be able to recognize when enough's enough, when it's time to pull out that digit or hand, to then be dried, inked, and printed.

Sodium hydroxide might very well factor in Hernández Cárdenas' process. But we can still really only make educated guesses. When I asked Anderson if the lab in Tucson would ever consider doing a full-body rehydration, be it in sodium hydroxide or something else, he expressed reservations.

"Logistically, it's very difficult," Anderson told me. "I don't see us going to that length."

In Anderson's view, unless you're looking for moles, scars, and tattoos, it just doesn't make sense to stick an entire body into a vat of lye, say. Besides, he continued, "we don't have a place to put bathtub-sized containers for 20, 30, 40 people who might benefit" from it. He added that he's not aware of a single medical examiner's office in the US doing full-body rehydrations.

Dr. Elizabeth Gardner, a forensic researcher at University of Alabama - Birmingham, corroborated that claim. She, too, said she doesn't know of anyone in America doing full-body rehydration R&D akin to Hernández Cárdenas. Gardner is, however, one of a small handful of players in the international forensic community who've seen first hand a mummified body rehydrating in Hernández Cárdenas' Jacuzzi at the forensic lab in Juarez.

"It was quite amazing. It looked like a relatively fresh body," Gardner recalled. "I think he does a very good job."


We might never know how Hernández Cárdenas does what he does. But we do know he's got his work cut out for him.


Juarez may no longer be the No. 1 most dangerous city in the world, a title it held as recently as 2009. But the city is still no stranger to death. It sits at the intersection of a coveted drug smuggling corridor (about 90 percent of the cocaine that ends up in the US today is muled through Mexico, mind you), the dumping grounds for exploited female laborers, and a high-traffic immigrant crossing.

To give you a rough idea of the scope of the bloodshed: Nearly 140,000 homicides were logged in Mexico between 2007 and 2013, according to figures from Mexico's National Commission of Public Safety and the National Institute of Statistics, Geography and Informatics.

American figures paint a similarly tragic picture: The US State Department's 2013 Country Reports on Human Rights Practices puts the number of people disappeared in Mexico between 2006 and 2012 at 26,121. Of all the unidentified cadavers zipped into numbered body bags and either stored in morgue freezers or laid to rest in mass graves across Mexico, the report adds, 7,000 trace back to that same six-year period, arguably the bloodiest stretch in the ongoing drug wars.

If anything, this wave of violence has given rise to a class of experts in various fields, from ballistics to body analysis to forensic dentistry, many of whom look to Hernández Cárdenas as a sort of mentor. The question, then, is why does he do what he does?

Around the 96-hour mark, after rotating our body in Jacuzzi, the doctor took us out to the Panteon Municipal San Rafael, a sprawling mass grave on the outskirts of Juarez. Roughly 5,000 bodies are buried here; at some point, many of them were unidentified. Some still are. If your body is putrefied enough, it'll automatically be marked 'unidentified,' and even if you are eventually identified, for health reasons your remains have to stay put for five years.


And yet as bodies here are identified, families can set up monuments for their loved ones. It's being able to provide a sense of closure for grieving families, left sometimes for years with little to no idea about what might have happened to a love one, that pushes Hernández Cárdenas to continuing paying out of pocket (and right in the face of continued violence and the specter of the drug cartels, no less) to demonstrate his method's real value. In some cases, he told me, it could mean that a family is given the opportunity to hold an open-casket funeral.


Back at the morgue, our body looks eerliy lifelike. He's been extracted from the Jacuzzi, and splayed out for a full examination. The stench is overwhelming. Cloying. My eyes water.

The doctor gives me the go ahead to touch the victim's face. His nose, cheeks, and lips are all plump to the touch, seemingly reinvigorated. The fingers, joints, and limbs are pliable. I can see small scars and abrasions from the accident. His forearms are scarred by self-inflicted wounds (suggesting he spent time fiending for drugs in jail, cutting himself to score pain killers), and all over his person are crude-looking tattoos, the sort you'd get after losing a bet in prison. One of them bears a striking resemblance to an ejaculating penis. Another, on one of the man's legs, reads: "sad memories."

These markers—the natural features, the wounds, the stick 'n poke tats, the fingerprints—will be the raw evidence though which criminal investigators here will comb in an effort to put a name to the face. Should they find a match, authorities will notify the victim's family. If nothing turns up, his final resting place will be in a mass grave. Whatever happens, Hernández Cárdenas will continue amassing a macabre, if redemptive body of work.

Three months after we visited Hernández Cárdenas and observed his full-body rehydration process for ourselves, we got word that a match was found based on the fingerprints pulled from the victim's rehydrated hands. His family has been notified. This marks the third known missing-person case resolved as a result of the doctor's full-body technique.