Investigators have decided to end a desperate 20-year search for a plane which crashed into a lake - killing all the 58 people on board.

The Northwest Orient Flight 2501 tragedy actually happened in 1950 but, since 2004, a dedicated team at non-profit organisation Michigan Shipwreck Association has engaged in a huge mission to find the bodies and remains of the plane. The crash was, at the time, the worst aviation disaster in US history and saw flight controllers lose radio contact with the aircraft, which reportedly experienced engine problems and careered into Lake Michigan.

Only body fragments of the 58 victims have been discovered and the wreckage has never been recovered. Michigan Shipwreck Association used sonar technology and even got support from an acclaimed adventure writer amid the 21-year mission to find the remains.

It was to no avail but the decision to halt the search has left the organisation with mixed feelings. Valerie van Heest, executive director, said: "It’s a hard thing to have to say because part of me feels like we have failed, but we have done so much to keep memory of this accident and these victims at forefront that I feel like we’ve done better for them than if we’d found the wreckage."

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Scientists believe the plane, which was a propeller-driven DC-4, now in very limited use, broke up into pieces too small to be detected by side-scan sonar and likely "sunk into the muck" on the bottom. They reached this conclusion having scoured the 700 square miles (1,813 square kilometers) of Lake Michigan, one of the largest lakes in the world.

The plane left LaGuardia Airport in New York City at night on June 23, 1950, with two stops planned on the route to Seattle. An intense storm suddenly appeared and the plane went down. Debris and body parts washed ashore in South Haven, Michigan.

Ms van Heest continued: "We know this plane hit the water with great force, and we know there was no way to survive this." The expert has now written a book Fatal Crossing, which is about the mystery.

Clive Cussler, an author whose adventure fiction has sold in the millions, financially supported a search until 2017. Also known for his own shipwreck hunting and underwater exploits, Mr Cussler died in 2020. Writing in 2018, the author said: "I hope someday the families of those lost will have closure." Mystery, though, remains for any living families of the 55 passengers and three crew members, who were travelling on the plane 75 years ago.

Further atrocities have become the US' worst aviation disasters in the decades since, not least the American Airlines Flight 191 disaster on May 25, 1979. Some 273 people died when the McDonnell Douglas DC-10's engine detached from the wing, causing a loss of control as it took off at O'Hare International Airport in Chicago, Illinois.