Nearly every war has missing soldiers, but those who did not return from Vietnam are the subject of long-lasting rumor that they are still being held prisoner.

The rumor can serve multiple purposes. For loved ones, it is a means of holding out hope their friends and relatives are still alive. For those with a more jaded view, it is part of a conspiracy theory aimed at no-good commies and/or corrupt U.S. government officials.

When the war ended with the signing of Paris Peace Accords, the 591 known American POWs were released in exchange for a U.S. withdrawal. Besides this, there were 2,646 service members listed as missing in action. About 1,000 of those have since been accounted for, either through their remains being identified, or having been found alive in the U.S. or overseas.

The idea that some service members might still be held captive began after the fall of Saigon in the spring of 1975. Part of this was because U.S. investigators lacked access to the battlefields and sites of former POW camps. Around this time, a Vietnamese family moved into my neighborhood. They were part of the influx of refugees, some of whom brought with them tales of having seen Americans still in captivity.

But since the late 1980s, U.S. officials have had full access to battlefields and former POW locations, and Southeast Asian nations have cooperated, allowing Americans to maintain research offices in their countries. In these 30 years of increased joint action and investigations, no American POWs have been found in Vietnam, Cambodia, or Laos. The only missing service members to show up alive were those who deserted or otherwise were lost in military bureaucracy, and none of these had been held after the Accords signing.

According to a 1992 New York Times article, reports from refugees were investigated by the Defense Intelligence Agency. The majority of the sightings, however, were of Americans who returned in 1973. About sixteen sightings were unresolved. The article explains that, according to DIA officials, “Most of the unresolved cases may not be related to American prisoners of war because they describe individuals who were not under guard, but were with Vietnamese wives and families, or were walking freely in Saigon. They could be Soviet advisers or Western European Diplomats.”

War represents a stain on mankind, the Viet Cong and North Vietnamese military engaged in barbarism, and POW camps in Vietnam were unconscionable violations of human rights. Further, many were buried deep in almost impenetrable jungles. With all this, it would seem not implausible that unscrupulous types could hold onto prisoners, for slavery, future bargaining, or simple cruelty. However, decades of sustained searching and investigation in periods of openness between former combatants have yielded nothing. The sites could have been moved, the cooperation could have been a ruse, but speculation like this is not the same as proof, which has never been forthcoming.

There have been far more detached-from-reality conspiracy theories than this one, but believers are still vulnerable to falling for a defining trait of conspiracy theories: The lack of evidence being seen as the evidence. To staunch believers, the lack of recovered, living POWs shows the extent and efficiency of the system that keeps them hidden.

Further, any documentation with contrary information is considered part of an governement cover-up. For example, according to Brian Dunning of Skeptoid, a Library of Congress website, “POW/MIA Databases and Documents contains more than 150,000 declassified documents from the Defense POW/Missing Personnel Office. This source allows a by-name search of MIAs and POWs, which will produce documents related to the searched individual. While this indicates transparency, a cynic would consider it a deflection meant to convince the gullible. In conspiracy theory parlance, it is merely a continuation of the official narrative.”

Proving that there was never a single POW held past 1973 would be impossible, but it is not on the skeptics to disprove a point. Rather, we should examine the best available evidence without bias and follow Occam’s Razor and the conclusions to their logical ends. Between the aforementioned website, POW databases, and the continued unearthing of MIA remains, claims of surviving prisoners seems untenable.

As with Bigfoot, each year that goes by without a confirmation of U.S. prisoners being held is a sign of its increasing unlikelihood. We know some that some MIA soldiers died in combat, some deserted, and some assumed aliases. We cannot completely dismiss the idea that some of them were held after the war, perhaps even still today. But a thousand pieces of hearsay, speculation, and third-hand reports do not equal one solid piece of proof.