It’s all about the shoes.

Since 2007, on 13 different occasions, human feet have washed up on the British Columbia shoreline. The most recent foot was discovered near Port Renfrew this month.

In each case the foot has been found inside a running shoe.

The sudden and regular appearance of the disembodied feet led to speculation that perhaps a serial killer was on the loose, leaving the body parts behind as grisly trophies.

Others wondered if plane or boat accidents at sea were the reason. In 2008, after the sixth foot had washed ashore, Vancouver Sun readers suggested it could be "anyone who works with cadavers — some university students having a good laugh."

Darryl Dyck / Canadian Press

The reason these feet keep showing up on the beach is not a mystery, though. Just look at the packaging.

"Something you'll notice is that the only feet washing up are in running shoes," Gail Anderson, a forensic expert at Simon Fraser University's school of criminology, told BuzzFeed Canada. "They're not washing up in stilettos or sandals, or as bare feet."

Thousands of people die at sea every year, and any body that ends up in the ocean naturally starts to disarticulate, or break down, as scavengers go about their work.

RCMP

Anderson's own experiments with pig carcasses show that this process can take as little as a few days or as long as several months.

These blackened bone fragments are all that remain of a whole pig carcass after crabs and other scavengers got to it.

"But these [feet] are being held together in that shoe and in that sock," Anderson said. "So very likely the tissue isn't being eaten."

She said it's also common for the feet to be saponified — that is, for the fatty tissue to literally turn to soap. "It's a strange waxy, putty kind of material and pretty much nothing eats it," Anderson said.

Gail Anderson / Ocean Networks / Via oceannetworks.ca

Lastly, the materials in a running shoe also help the feet avoid a watery grave at the bottom of the ocean. "It's basically a floatation device, so it's going to hold it all together and get it washed ashore," Anderson said.

Anderson believes after the first few discoveries, people simply started to be on the lookout for random shoes on the beach, and that's why it seems like such a recent phenomenon. She doesn't blame people for assuming foul play, either, though suicide is probably more likely as a cause of death.

"If you're not in the forensic field and you find a body part, you're naturally going to freak," she said.

Aquagreenmarine / Getty Images

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