A few hours later the bodies of his wife Carolyn and sister-in-law Lauren Bessette were also found.

Hampered by strong currents and cold temperatures, US Navy and Coast Guard salvage and search teams had combed the waters around near Martha's Vineyard, off the coast of Massachusetts.

The single engine Piper Saratoga plane, which reportedly lay 30m deep, was discovered by remote-controlled submersible vehicles using sonar, rather than by diving teams.

Stephen Sackur reports on the search operation from Cape Cod

The remains and wreckage were found at night, but officials kept the details secret for several hours out of respect for the family.

Experts are still deciding how best to conduct the salvage operation.

Four ships involved

Divers from the Massachusetts State Police and the Navy salvage vessel USS Grasp were part of the underwater search effort.

Massachusetts State Police divers join in the search effort

Also involved were the Rude, a National Oceanic and Atmospheric Administration research ship, the NOAA's Whiting, and the Coast Guard cutter Willow.

Working in visibility of less than eight feet, the divers were only able to search for 15 minutes at a time, due to the depth of the water.

Beneath the ocean's surface, the operation had to contend with crabs, octopus, seaweed and debris.

One object that sonar maps showed might have been a piece of the plane turned out to be a 14-foot rock.

'Splash point' located

Search operations were concentrated on two key areas

Divers initially honed down the number of target sites being searched to just two, using radar information that indicated where the plane hit the water.

"We have a theoretical splash point that we feel very good about," said Admiral Richard Larrabee of the US Coast Guard.