A particularly grisly mystery in the Pacific Nothwest – solved by science

You never know what might be floating around - a repost of our most-read piece from this week last year (worth another spin): 

Over the course of 12 years, a total of 15 human feet washed ashore along the Salish Sea. The unsettling discoveries prompted talk of serial killers, aliens, and psychics. The truth is even more unexpected.

On August 20, 2007, a 12-year-old girl spotted a lone blue-and-white running shoe - a men’s size 12 - on a beach of British Columbia’s Jedediah Island. She looked inside, and found a sock. She looked inside the sock, and found a foot.

Six days later on nearby Gabriola Island, a Vancouver couple enjoying a seaside hike came across a black-and-white Reebok. Inside it was another decomposing foot. It, too, was a men’s size 12. The two feet clearly didn’t belong to the same person; not only were the shoes themselves different, but they both contained right feet.

Police were stunned. “Two being found in such a short period of time is quite suspicious,” Garry Cox of the Royal Canadian Mounted Police told the Vancouver Sun. “Finding one foot is like a million to one odds, but to find two is crazy. I’ve heard of dancers with two left feet, but come on.”

The next year, five more feet appeared on nearby Canadian beaches. The discoveries ratcheted up the public’s fears, and media speculation soared. Was a serial killer on the loose? Did he have something against feet?

Over the course of the next 12 years, a total of 15 feet washed ashore in the area around Vancouver Island, a network of waterways called the Salish Sea. Six more turned up in Puget Sound, which lies across the U.S. border at the southern end of the sea. With the exception of one foot wearing an old hiking boot, all of them were encased in sneakers.

The sneaker-clad feet became famous, even garnering their own Wikipedia page. And with fame came hoaxes: pranksters stuffed shoes with chicken bones or skeletonized dog paws and scattered them along Canadian shorelines.

Tipsters called police with all manner of theories about the origins of the feet. “We get some very interesting tips that come in about serial killers, or containers full of migrants that are sitting at the bottom of the ocean. Aliens—had that one as well,” says Laura Yazedjian, a forensic anthropologist who works as a human identification specialist for the British Columbia Coroners Service. “And occasionally a psychic. Actually, pretty much every single time, a psychic will call and offer to help.”

But this type of mystery, it turns out, requires scientific, rather than criminal investigation (or psychics). In fact, science can answer all of the obvious questions—for example, why are feet, and not entire bodies, washing ashore? And why are they showing up on this particular stretch of British Columbia’s shores? But the research that has addressed these questions is anything but obvious. To understand how the feet got where they did, we have to follow some unexpected lines of inquiry, involving everything from the science of sinking to the decomposition of pigs and spreading oil spills.

To sink or swim

To begin, we must understand what happens to a dead body once it’s in the water. So let’s follow the adventures of a seafaring cadaver.

Once in the water, a cadaver’s first move will be either to float or to sink. This is a surprisingly crucial step, as it will help determine what happens next. A floating object will be carried with the winds and by surface currents, and might soon wash ashore. A sinker, on the other hand, might remain in place, or be tugged in a different direction by deeper currents. What’s more, a floating body, exposed to air, will decompose differently from one that sinks, with ramifications for the fate of its feet.

One might assume that a drowned person will sink because their lungs are full of water, and that a cadaver’s air-filled lungs would otherwise act as a flotation device. But the reality is not so simple. Using data collected in 1942, E.R. Donoghue of the Armed Forces Institute of Pathology set out to settle the matter in a 1977 article titled “Human Body Buoyancy: A Study of 98 Men.” 

The 98 men in question were “healthy U.S. Navy men in the 20-to-40-year age group.” Each was suspended underwater and weighed both with his lungs full of air, and after expelling as much air as possible. It’s no easy task to wait to be weighed underwater with no air in your lungs - but again, these were Navy men.

With their lungs fully inflated with air, all the men floated. But once they had emptied their lungs (as would be the case with a dead body) most of the men sank in freshwater; only 7 percent floated. In seawater, though, people are more buoyant: 69 percent of the Navy men would float if they were dead and naked in the ocean, Donoghue estimated. But it was a close call; just a little added weight, such as heavy clothing or water in the lungs, could cause a body to sink. In the end, the data suggest, cadavers are overall more likely to sink than to float, and people who drown are the most likely to sink.

What’s more, once a body sinks, it tends to go straight to the bottom. Sometimes, an underwater cadaver will eventually bloat, just like a body on land, causing it to bob to the surface. But that doesn’t always happen, says Yazedjian, the investigator from the Coroners Service. In a deep lake or ocean, it may never come back up. Not only does the cold inhibit decay in deep waters, but the greater water pressure there also prevents any gases from expanding and causing bodies to float. Instead, other microbial processes take over and convert a sunken body’s tissues to adipocere, “this kind of waxy, soaplike tissue,” she says. Adipocere can persist for years, even centuries, in a low-oxygen environment.

And that’s exactly what Yazedjian saw on the feet she examined from the Salish Sea. They were covered in adipocere, suggesting that the cadavers sank, and remained underwater as they decomposed. That could explain where the remainders of the bodies were: They sank and stayed sunken.

But why didn’t the feet stay down with the bodies?

Feet set sail

To understand how the feet set sail sans bodies, we need to know how a human body might decompose underwater, and whether its feet are prone to pop off and float away. Scientists study the process of human cadaver decomposition at several U.S. forensic research sites, but these are all on land; none had ventured to drop a body into the ocean. (Find out how cadavers help advance all kinds of scientific research.)

But our investigation is not dead in the water. In the summer of 2007, forensic scientist Gail Anderson of Simon Fraser University was conducting a study for the Canadian Police Research Centre to understand how quickly a homicide victim would decompose in the ocean. Because ethics rules preclude using a human body, she used a dead pig instead. Pigs have often been used in forensic research as stand-ins for a human body; they are roughly comparable in size and are quite similar biologically.

Even better, Anderson conducted her study in the Salish Sea, not far from where the third human foot would be found six months later. Her team dropped the dead pig into the water, and it promptly sank 308 feet to the seafloor.

What happened next was not pretty. The pig carcass was quickly eaten by a large and unruly mob of shrimp, lobsters, and Dungeness crabs, starting with the “expected areas, the anus region and the facial orifices,” Anderson reported. It was as if a Red Lobster buffet had risen up to exact its revenge.

Since then, Anderson has dropped more pigs even deeper in the Strait of Georgia, a main channel of the Salish Sea, and found that in some cases scavengers can skeletonize a carcass in less than four days.

So what about the feet?

It turns out that underwater scavengers like crustaceans will work around bones and other tough obstacles, preferring to pick apart softer tissues. And unlike the bony ball-and-socket joints that join our legs to our hips, our ankles are made up mostly of soft stuff: ligaments and other connective tissue. So it follows that a sunken, shoe-wearing cadaver in the Salish Sea is likely to be chewed apart by scavengers, and to have its feet disarticulated from the rest of the body in short order.

And as Yazedjian tells me, all of the Salish Sea feet appeared to have been separated from their bodies by natural processes, like scavenging and decomposition. “Please don’t call them ‘severed feet,’” she warns. Severed means that someone cut them off, she explains, and the Coroners Service never found cut marks on any of the bones to suggest that.

What’s more, feet wearing sneakers made in the last decade or so would almost certainly float. Not only have gas-filled pockets become common in sneaker soles (and they’re visible in some sneakers found in the Salish Sea), but around that time, the foams used in sneaker soles started to be noticeably lighter, with more air mixed in. In other words, they’ve become buoyant.

Blowing in the wind

So now we have a seafaring foot, sneaker-clad and ready to sail. But why the Salish Sea? If feet are likely to float away from dead bodies, why aren’t beaches everywhere littered with them?

Possibly the man who knows the most about how and where things end up in the Salish Sea is Parker MacCready, a professor of oceanography at the University of Washington in Seattle. He’s built a three-dimensional computer simulation of the coastal ocean of the Pacific Northwest, including the Salish Sea.

“It’s all realistic,” he says, “in the sense that it has realistic tides, winds, rivers, and ocean conditions.” The simulation is called LiveOcean, and as we talk on the phone, we both watch it running on his website: Brightly colored water sloshes around a map according to that day’s weather and tides.

MacCready uses the model to predict where an oil spill would travel over the course of three days. As we watch, black blobs appear near Seattle and Tacoma, simulating the hypothetical oil spill, and immediately start flowing north into Puget Sound, sailing on rainbow-colored swirls that depict moving waters of various salinities. Soon, the blobs break apart into thin streamers and dots, splitting and sloshing in every direction as tides and currents push them around.

As it turns out, LiveOcean reveals an important key to the mystery - why so many feet are washing up here in particular. The answer? The Salish Sea has the perfect storm of feet-ensnaring properties.

The reasons add up. First, it’s an unusually large and complex body of inland water, which acts as a trap. As MacCready’s model shows, once something goes in the water, it might wash ashore in plenty of places - but it’s still within the Salish Sea. Second, the prevailing winds are westerlies, so they bring stuff in from the ocean, rather than pushing it out to sea.

And finally, there’s something MacCready’s model doesn’t show, but he points it out. You see a lot of folks wearing sneakers at the beach in the Pacific Northwest, where many choose to hike among the slippery rocks. Taken together, all these factors - plus the cold deep waters and healthy scavenger populations—make the Salish the ideal foot magnet.

But who were the owners of the Salish Sea feet?

The first place investigators looked was missing person reports. The Coroners Service has now compared DNA from each foot to a database of more than 500 missing people in British Columbia, plus Canada’s new National Missing Persons DNA Program, launched in 2018.

Using DNA, the team linked nine of the feet to seven missing people. (For two, both feet were found; most had been missing for a year or more.) The longest-missing person had disappeared in 1985; his foot in a hiking boot was found in 2011. In the most recent case, the foot of a young man who disappeared in 2016 was documented to have washed up on an island in Puget Sound in 2019.

The Coroners Service in British Columbia reports that none of the Canadian cases so far have been found to result from homicide. In some cases, it became clear that the person had died by accident or suicide, as in the case of one woman who jumped from a bridge. Other times, circumstances were hazier. In the case of a young man whose foot was found in Puget Sound in 2019, U.S. police said they couldn’t rule out either homicide or suicide. And for those who vanished without witnesses, it’s nearly impossible to glean a cause of death from a foot alone.

As of this writing, five of the feet in British Columbia remain unidentified.

Some, no doubt, will be disappointed to learn that a serial killer wasn’t stalking the rocky shores of the Pacific Northwest. Although The Mystery of the Floating Feet would make a great title, it probably won’t become a Netflix original documentary - especially once producers discover that their footage would mostly feature crabs dragging pig entrails across the ocean floor, rather than lingering shots of a serial killer’s high school yearbook photo.

That’s the difference between armchair CSI fans and actual forensic scientists: A scientist wants to know the right answer, even if it’s mundane. But if you think about it, it’s actually pretty exciting that nature hands us clues to what would otherwise probably remain cold cases.

Even years later, a missing person might be found, his or her death investigated, all because of a peculiar combination of foot physiology, scavenger behavior, and footwear technology.

Sometimes, such unexpected clues lead us places we never thought we’d go, if only we are willing, patient, and brave enough to follow them. And sometimes they do it wearing sneakers.

 - AUTHOR: ERIKA ENGELHAUPT

 - SOURCE: NATIONAL GEOGRAPHIC

ORIGINAL ARTICLE HERE