MADISON, Wis. (AP) — Searchers announced Thursday they’ve discovered what they believe is the wreckage of World War II ace Richard Bong’s plane in the South Pacific.

The Richard I. Bong Veterans Historical Center in Superior, Wisconsin, and the nonprofit World War II historical preservation group Pacific Wrecks announced in March they were launching a joint search for Bong’s Lockheed P-38 Lightning fighter. Bong nicknamed the plane “Marge” after his girlfriend, Marge Vattendahl.

Another pilot, Thomas Malone, was flying the plane in March 1944 over what is now known as Papua New Guinea when engine failure sent it into a spin. Malone bailed out before the plane crashed in the jungle.

The expedition’s leader, Pacific Wrecks Director Justin Taylan, said in a news release that the search team discovered the wreckage in the jungles of Papua New Guinea’s Madang Province. He released photos of himself in the jungle with chunks of metal on the ground taken May 15.

In one photo he points to what the caption calls a wing tip from the plane stamped with “993,” the last three numbers of the plane’s serial number. Enlarging the photo shows markings that could be two “9s” but they’re obscured by what might be dirt or rust and difficult to make out. Another photo shows a piece of metal stamped with “Model P-38 JK.”

“The plane’s association with Richard Bong makes it one of the most significant World War II aircraft in the world,” Taylan said in the news release.

Bong, who grew up in Poplar, Wisconsin, is credited with shooting down 40 Japanese aircraft during World War II. He plastered a blow-up of Vattendahl’s portrait on the nose of his plane, according to a Pacific Wrecks summary of the plane’s service.

Bong shot down more planes than any other American pilot. Gen. Douglas MacArthur awarded him the Medal of Honor, the U.S. military’s highest decoration, in 1944.

Bong and Vattendahl eventually married in 1945. Bong was assigned to duty as a test pilot in Burbank, California, after three combat tours in the South Pacific. He was killed on Aug. 6, 1945, when a P-80 jet fighter he was testing crashed. He died on the same day the United States dropped an atomic bomb on Hiroshima.

Vattendahl was 21 at the time of Bong’s death. She went on to become a model and a magazine publisher in Los Angeles. She died in September 2003 in Superior.

A bridge connecting Superior and Duluth, Minnesota, is named for Bong.

“The Bong family is very excited about this discovery,” James Bong, Richard Bong’s nephew, said in the news release. “It is amazing and incredible that ‘Marge’ has been found and identified.”