By Ian Gunn
BBC News, Vancouver
The police in Canada have a gruesome mystery to puzzle over as after a human foot was found washed up on a beach near the west-coast city of Vancouver.
It is the fourth such foot to be found on beaches in the area in the past eight months.
All four of the feet were wearing socks and running shoes and all four had been in the sea for some time.
But police say they have no idea how or why they came to be there and hope DNA tests, now under way, may help.
Last August, two human feet washed up on the beaches of two small islands north of Vancouver. Then in February another single, right foot drifted ashore.
And now a fourth - again a right foot - has been found - this time on a beach in suburban Vancouver. The city's newspapers and coffee shops are buzzing with theories to explain the mystery.
Organised crime, boating accidents - even the 2004 Asian tsunami - are all being offered as possible, if amateur, solutions. The professional detectives are saying very little.
The police say they are treating the cases as suspicious, but are quick to play down the wilder rumours about gangs and tsunamis. Forensic experts say it is actually quite common for body parts to become separated after they have been in the water for a long time.
Why only right feet have been found is still a complete mystery.
The police say it is possible the feet come from the passengers aboard a small plane which crashed into the water in the region several years ago - their bodies were never recovered.
But the police caution that DNA test results are needed before they can say whether they have managed to solve the mystery of the four right feet.