A retired Idaho couple is back in B.C. looking to recover the body of a local man believed to have drowned at Harrison Lake in early June.

In April, Gene and Sandy Raltson recovered the bodies of Brendan Wilson and Austin Kingsborough, two teenagers, who drowned in Nicola Lake near Merritt.

Now they are trying to find the body of Raymond Salmen, who is presumed drowned after disappearing from his campsite at Harrison Lake last month.

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Daniela Salmen's husband Raymond went missing from his campsite at Harrison Lake last month. (CBC)

His wife, Daniela Salmen, says she is grateful for the Ralston's charity.

"What would we do, I just can't just do nothing. You have the RCMP say that they're not able to recover and we're sorry for your loss, and you can't, you can't just leave it like that," she said.

The Ralstons own their own side-scan sonar, which makes images of the deepest recesses of lakes using sound. They help families recover drowning victims for expenses only.

"Generally when we are bringing someone up, we talk to them and tell them, 'you're coming home, we're bringing you home'," said Gene Ralston.

In the past 10 years, Gene and his wife have recovered close to 90 bodies using what they call their "underwater robot", which allows them to search as deep as 850 feet with 1,000 feet of cable.

"[These are] probably the only two people in North America who do that out of the goodness of their hearts," said Marvin Anderson of Kent Harrison Search and Rescue.

"We'd have to spend a lot of money to get to the state of the Ralston's boat, we just don't have the resources," Anderson said.

With files from the CBC's Deborah Goble