Amelia Earhart and her navigator Fred Noonan disappeared in July 1937 and have never been found. AP file photo

"I am sure we are looking in the right spot," Quigg said during a visit last week to the Aviation Museum of Kentucky in Lexington. "I think eventually we will find the smoking gun that it takes to conclusively say this is where the flight ended."

Earhart and her navigator Fred Noonan disappeared in July 1937 and have never been found.

Quigg, 45, is an archaeological researcher who spent a month on Nikumaroro Island this summer looking for clues as a member of The International Group for Historic Aircraft Recovery.

Previously, another team that went there found aluminum that could have come from Earhart's plane, along with pieces of a shoe.

The Lockheed Electra Flying Laboratory that Earhart flew on her doomed around-the-world flight was funded, in part, by the Purdue Research Foundation. Earhart had been a women's career counselor and visiting instructor at Purdue University in West Lafayette, Ind., for two years before the flight.

Nikumaroro is in the Phoenix Islands, southwest of Hawai'i. It is three miles long and 1.5 miles wide.

Some historians dispute the evidence, but Quigg disagrees.

He said the Navy sent a battleship with observation planes to the area shortly after Earhart disappeared because of radio transmissions on her frequency.