The man, who claimed to be missing US Green Beret John H. Robertson, has been identified as a Vietnamese man of French ancestry, Dang Ngoc Than.
US Authorities say Ngoc has a history of pretending to be US Army veterans, and his story has been previously refuted by DNA tests.
But Ngoc’s claims generated an explosion of interest this week with the premier of documentary Unclaimed, in which he stated he had survived a helicopter crash 44 years ago and was kept prisoner by the North Vietnamese.
Ngoc claimed in the film that he was held in a bamboo cage and tortured for about a year, before going on to marry a nurse who took care of him and brought him back to health.
But the United States Defense Department says the man claiming to be Robertson has been DNA tested and his claims are false.
Reports say US investigators interviewed Ngoc in 2004 and 2009, to verify his claims that he was a missing US soldier.
If he had been proven to be Robertson, he would have been entitled to back pay and veterans’ benefits from the US government.
But Ngoc admitted under questioning that he was making up his story, and was in fact Vietnamese.
Nearly 2,000 US soldiers were unaccounted for after the Vietnam War ended in 1975, and some were kept prisoner in Vietnam for years afterward.
US authorities say Ngoc has been impersonating missing US soldiers since the 1980s, and reports say he may have conned US veterans’ groups out of thousands of dollars during that time.