Blaine Gibson, an American lawyer leading a self-funded hunt for missing Malaysian Airlines Flight 370, handed over six pieces of debris found on Madagascar to Malaysian investigators on Tuesday.
Gibson said one piece he found might prove why the plane crashed.
"If the third piece, the monitor case, is confirmed to be from MH 370, it proves, tragically, that the main body of the cabin broke apart in a forceful impact ... (and) definitely not a controlled ditching," he said. "The barnacles on board will hopefully provide some clues as to the location of the crash site and route followed."
Gibson found the debris in June on the island of Nosy Boraha, off the east coast of Madagascar.
MH370's disappearance is one of the world's biggest aviation mysteries.
The plane vanished from radar while en route from Kuala Lumpur, Malaysia, to Beijing, with 239 people on board, on March 8, 2014.
Since July 2015, about six pieces of wreckage have been confirmed as likely coming from the missing plane, although not all pieces could be completely verified.
In October, a fragment of plane wing discovered in Mauritius in May was confirmed as coming from MH370, Australia's Transport Safety Bureau said.
Earlier in 2016, Gibson found a piece of a plane wreckage off the Mozambique coast.
Australian investigators later said it "almost certainly" came from MH370.
Gibson, from Seattle, is leading an exhaustive search that has taken him from the Maldives to Mauritius and Myanmar.
Meanwhile, the Chinese search and rescue vessel looking for the missing plane has wrapped up its mission in the Indian Ocean, according to the ATSB.
In July, the governments of Malaysia, Australia and China agreed the search for MH370 will be suspended if no evidence of the plane is found upon the completion of the search area.