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A warplane encrusted with coral lies upside down on the seafloor of Saipan’s harbor, its landing struts thrust awkwardly upward as colorful fish weave in and out of the exposed fuselage, engine and gun turret. The wreckage is slowly being subsumed by the reef in the shallow blue waters of the tropical lagoon, but its story is far from over.

Three crew members had been aboard the Grumman TBF Avenger as it went down, likely during or after the 1944 Battle of Saipan, when US forces launched an assault to secure the Northern Mariana Islands during World War II.

American military officials viewed Saipan, the largest island in the Mariana archipelago, as a key base for operations in the Pacific, and the battle marked a pivotal victory for the US. Only one of the downed plane’s crew, however, walked away from the conflict; the remains of the other two men are presumed submerged, neither recovered nor forgotten.

Now, the Avenger wreck is one focal point for scientists in a cutting-edge endeavor to understand whether traces of decades-old DNA can be preserved and detected at wreck sites. Working with the US Defense POW/MIA Accounting Agency, the researchers are testing innovative technology that uses environmental DNA, or eDNA, found in soil, sediment and water as a biological scouting mechanism. If successful, the method could help locate the remains of the missing service members — and perhaps thousands more.

The aftermath of a US naval bombardment on the west coast of Saipan during World War II. Hulton Deutsch Collection/Corbis/Getty Images

The Defense POW/MIA Accounting Agency, or DPAA, is tasked with recovering the remains of the more than 40,000 American troops presumed lost at sea since World War II. Officials are hoping eDNA will speed up the search.

“We’re looking for ways to meet some of the challenges that are inherent in underwater investigations … some of the most challenging sites for us,” said Jesse Stephen, an archaeologist who is the DPAA’s chief of innovation.

Investigating an underwater site, he said, tends to be more complicated than looking for missing service members on land for several reasons. There is typically a dearth of historical information about the conditions in which the vehicle went missing, and locating a sunken aircraft or a large ship in the vastness of the ocean is difficult and costly. Even when a site has been located, it’s hard to find human remains, which often become separated from a wreckage due to impact force or the movement of water.

“We wanted to explore how you could you use eDNA as a general site investigation tool specifically to determine the likely presence or absence of human remains,” Stephen said.

The decaying Avenger is one of a dozen wrecks in three very different underwater environments — the western Pacific Ocea