Since 2007, nine disembodied feet, most still inside sneakers, have washed up off the coasts of British Columbia and Washington state, sparking an international guessing game over their ghoulish origins.

Among the most popular theories: that the feet belonged to victims of the 2004 Asian tsunami, or illegal stowaways, or were the final remains of the victims of a serial killer who had come up with a highly original calling card.

Finally, the mystery has been cracked, and the cause is as pedestrian as it is tragic: These feet, according the coroner’s office of British Columbia, almost all belong to suicides, and almost all of them jumped from bridges spanning the powerful Fraser River, which flows into the Pacific Ocean at Vancouver.

Once the bodies sank — a dead body will expel the gases that keep it afloat within hours — the body begins to decompose, limbs begin to separate and marine life begins to feed.

Feet shod in polymer-based sneakers, however, survived — fish can’t chew through them.

“It’s very explainable,” said coroner Stephen Fonseca, who’s worked on each of the cases. “The unusual nature of this is that the feet were found in a very short period of time.”

The average rate of recorded suicides in British Columbia is 500 a year — but the stigma is such that British Columbia has a very high threshold for putting that down as cause of death, and experts believe that the number of suicides annually may be much higher.

‘We don’t know how many there are for sure,” said Ian Ross, executive director of the Crisis Intervention and Suicide Prevention Center of BC. “There are a lot of single-car accidents. People who go off bridges — did they jump, or were they pushed? There’s such a stigma around suicides that it’s almost better left unsaid.”

Aside from the famed dreary weather that cloaks the Pacific Northwest, Ross thinks that the high density of immigrants to the region is a factor. ‘There are so many people coming from countries where suicide is against the law,” Ross said.

Some suicides, Ross theorizes, are people who no longer fear retribution for their families; most others, he thinks, are immigrants who are struggling to adjust.

And then there are just the bereft.

“We do have a lot,” Fonseca said. “You have to appreciate that we often don’t report on suicides.”

The shame remains such that two cases, by law, remain technically unsolved, though Fonseca admits that “those individuals were distraught. But I can’t say they [were] suicides, because they don’t meet the criteria.”

In order to determine how those individuals died, Fonseca and his team of five had to identify the remains. Though each foot was remarkably well preserved, it’s a part of the body that offers very few clues.

“You can’t tell race or age,” Fonseca says. A coroner can, however, determine gender, and whether the victim was an adolescent or an adult, based on how the bones are fused.

So Fonseca and his team worked backward, cross-referencing the sites of the found feet with missing-persons reports. They also investigated the origins of the shoes, mining product data, manufacturing details, where the shoes were produced, distributed and sold.

It was the missing-persons data base, however, that proved most valuable: In the case of the most recent foot, discovered on Nov. 5, 2011, it was quickly determined to be “definitely an accident,” Fonseca said.

For those disappointed by the un-glamorous causes of death — no natural disaster, no serial killer — Fonseca offered words of encouragement.

“I don’t think there’s a soul out there that doesn’t check every shoe they find on a beach,” he said. “I think there are a lot more cases out there.”