PARIS — After three failed searches over nearly two years, more than $28 million spent on scores of specialists and the latest in deep-sea technology, not to mention a number of embarrassing premature sightings, French air accident investigators finally found what they were looking for in a sandy plain nearly two and a half miles below the surface of the southern Atlantic Ocean.

At a spot no farther than six miles north of the last known location of Air France Flight 447, side-scan sonar detectors attached to a tiny unmanned submarine late Saturday stumbled across a field of metal debris strewn across the sandy ocean floor 600 miles off the coast of northern Brazil.

Within hours, another Remus 6000 drone submarine was transmitting a series of haunting black and white images to specialists aboard the main search vessel, the Alucia: two engines, ripped clear of the plane’s wing; bits of landing gear, a section of fuselage dotted with a row of windows.

And bodies.

“We weren’t prepared for that,” Robert Soulas, who lost his daughter and son-in-law in the crash, said of the discovery of the bodies. “We are now confronted with another trauma.”