VANCOUVER, B.C. -- And then there were five.

Five feet have washed ashore in the Strait of Georgia in British Columbia since last summer. And one man thinks he knows where they may have come from.

Most recently a left human foot was found partially submerged in water near Westham Island on Monday.

"A passerby noticed a shoe floating in the water, pulled it in and notified police," Delta Police Const. Sharlene Brooks said. "We're treating it as a criminal investigation."

The five feet have all been in shoes, but investigators have not determined whether the cases are related.

"We're certainly not discounting the possibility that this may be linked to the other recovered feet, but it's just too premature and very speculative for us to even entertain that right now," said Brooks.

The chief coroner says there's nothing to suggest foul play. The Royal Canadian Mounted Police say there's no evidence the feet were severed or removed from the owners' legs by force.

"Perhaps a plane going down, a boat going down, where a number of deaths have occurred - and they don't even have to be in our waters.

"And perhaps something has happened; the tide has shifted, another boat has hit it, something has happened to move it," said Dr. Gail Anderson with SFU Center for Forensic Research.

Kevin Deacock believes he may have been that "something" that happened.

Deacock's two brothers were killed in a plane crash off Quadra Island three years ago. He spent countless hours searching for their bodies and the bodies of two others on board.

"I dragged a hook along the bottom looking for the motor and I believe I could have stirred something up. It was two weeks after that that the first foot showed up," he said.

The coroner's office has collected DNA from three of the found feet and has asked relatives of the plane crash victims for DNA samples to see whether they're a match.

In May a passer-by found a human foot in a shoe on Kirkland Island in the South Arm of the Fraser River. Another right foot were found on the east side of Valdez Island in February.

And last August, a foot was found inside a man's Reebok sneaker on nearby Gabriola Island, just a few days after another foot was discovered by beachcombers on Jedidiah Island.

Westham Island is at the mouth of the Fraser River, about 15 miles south of Vancouver.

Curtis Ebbesmeyer, an oceanographer based in Seattle, Wash., said when a human body is submerged in the ocean, the main parts like arms, legs, hands, feet and the head are usually what come off the body.

He said his theory is that the feet came along as a result of an accident that might have happened up along the Fraser River, that washed down and spread out along the Straight of Georgia.

Ebbesmeyer said when the third foot was found the feet could have drifted from as far as 1,000 miles away. Ebbesmeyer said the feet could have been severed or detached from their bodies on their own.