A bone fragment. A skull section. A molar.
Such minuscule human remains as these recently enabled the United States military to identify service members missing for 36 years, ever since their AC-130 gunship named Spectre 13 was shot down during the Vietnam War.
The tiny size of the fragments attests to the steep challenge faced by investigators, even with the power of DNA testing, to give families the certainty that their loved one did die.
The bone pieces used in DNA testing are ideally at least the size of a quarter, according to Larry Greer, spokesman for the Defense POW/Missing Personnel Office at the Pentagon. But, with plane crashes, the impact and secondary explosions can obliterate much of the evidence, rendering remains too small to test.
And the more time passes, the less there is to find and examine. Wild animals scavenge. Locals might carry off remains - to perform a proper burial or to hand them over to authorities in hope of a reward. In Southeast Asia, the ground itself reclaims evidence: The soil is as acidic as orange juice, said Greer.
The U.S. government spends $105 million a year trying to locate and identify the 88,000 service members missing from past wars. More than 78,000 are from World War II; many will never be found because their ships sank. The next-biggest group, more than 8,100, are from the Korean War, with 1,761 missing from the Vietnam conflict.
At this point, Greer said, the mission is to recover the dead. "We have specialists out there whose sole job it is to investigate reports of live sightings, [but] they have not had a firsthand live sighting report in more than a decade," he said.
A team of more than 600 toils on MIA cases. That includes field investigators and forensic scientists at the Joint POW/MIA Accounting Command in Hawaii. Remains are tested at the Armed Forces DNA Identification Laboratory in Rockville.
Since 1973, the identified remains of 885 Vietnam vets have been returned to the U.S. Mortuary affairs. Officials such as Arthur Navarro meet families at that point. Some relatives reject the findings, which are based on DNA tests or dental records.
"They still think their loved one is out there; they're very bitter," said Navarro, based in San Antonio. Most relatives accept the findings.
Sometimes, the military informs families of additional remains after new excavations. In the case of Spectre 13, a 2006 dig yielded new remains to go with those found 20 years earlier that led to nine identifications. The plane went down in 1972 over Laos with 14 aboard.
This year, half of the 14 families learned of additional remains. Two declined to take receipt, Navarro said, possibly to avoid enduring another burial. (Four of the 14 crew members were identified for the first time, including Senior Master Sgt. James K. Caniford of Frederick. Only Lt. Col. Henry Brauner remains unidentified.)
DNA testing has aided the search considerably. Since 1991, 531 of the 855 MIA identifications have been made based on comparisons to DNA supplied by maternal-line relatives. That helps explain the surge in World War II identifications, which have outpaced those from Vietnam lately. Since 2005, 118 World War II soldiers and sailors have been identified, versus 84 from Vietnam, Cambodia and Laos.