The fate of U.S. defectors during the Vietnam War remains a mystery and the nature of U.S. government efforts to insure they would remain invisible remain a mystery. PNS commentator Douglas Valentine is the author of a book-length study of the activities of the Special Forces in Vietnam, entitled "The Phoenix Program," published in 1990. SECOND OF A TWO PART SERIES.

When the 1973 cease-fire was declared ending the war in Vietnam, an estimated 300 American deserters remained in South Vietnam. Only 268 took advantage of an amnesty offer in April 1975, according to Susan Katz Keating, author of the 1994 book, "Prisoners of Hope."

Goaded by alleged sightings of American POWs and MIAs by Vietnamese refugees, the search for defectors continued under the guise of an MIA-POW recovery effort. No one seemed to recall earlier U.S. government assertions that all POWs had been returned.

In 1987, the issue attracted public attention after Scott Barnes claimed to have photographed two American POWs in Laos. At the same time an official government commission announced there was a strong possibility of Americans in Laos and Vietnam -- including "voluntary stay-behinds: deserters, civilian contractors gone native, converts to Vietnamese religious sects, over-zealous missionaries, and Americans involved in drug trafficking."

Congress finally formed a select Committee on POW MIA affairs, following the publication in 1990 by the LA Times of a photograph allegedly showing three American POWs. (The photograph later turned out to be a scam by unscrupulous Cambodian officials). By 1991, according to Michael McConnell, in his 1995 book "Inside Hanoi's Secret Archives," only 57 firsthand sightings of live Americans remained unresolved, and most "were eventually determined to involve either American deserters (about 24 in number) or Soviet or Eastern Bloc technicians."

In 1991, working as a consultant to the BBC on the Phoenix program, I corroborated this information while interviewing Vietnamese living near Nui Ba Den Mountain, on the Cambodian border. I was tracking down rumors that two American men were living in the vicinity -- rumors that had already attracted the interest of official U.S. Government MIA POW search teams. My host told me of the hefty bribes these teams offered villagers for evidence of the missing men. "'Find the MIAs and the U.S. will bring your family to America,' they tell us."

This information was also corroborated by Anthony Poshepny (aka Tony Poe), the CIA agent then living in Thailand who had served as the model for Marlon Brando's Colonel Kurtz in Apocalypse Now! Poe told me that investigators planted evidence to fuel the MIA POW rumor mill, but the real objective was "to find 55 deserters, all criminals guilty of fragging (murdering with grenades) their officers, who had escaped from prison in 1973 and 74 and gone into the tunnels with the Viet Cong."

The Vietnamese did not want to turn these men over to the U.S., but they desperately needed the American dollars that would come with normalized relations. So they said nothing officially, but whenever possible took the bribes and then led U.S. search teams on a wild goose chase.

For me, the last sad, strange twist in the deserter story came in 1992, when C-SPAN aired Vietnam Revisited, a documentary about Senator John Kerry's (D-MA) trip to Vietnam to solve the mystery of American POWs and MIAs. I was surprised to see Kerry's interpreter was Jean Sauvageot who, during the war, had conducted secret prisoner exchanges for the CIA with the Viet Cong. These exchanges had opened up a secure channel of communication with the North Vietnamese which was then used to attempt to negotiate a cease fire that never happened in 1967.

I had interviewed Sauvageot myself in 1987 when he was a retired colonel and Vice President in charge of Asian operations for Northrup. He had also just returned from Hanoi with General John Vessey.

In April 1992 Sen. Kerry reported evidence of a "significant enough number" of deserters to take into account when evaluating reports of sightings of American servicemen unaccounted for after the war.

In 1993, according to Keating, the number of defectors had fallen to six. "The government has tracked them for years while simultaneously denying their existence," she writes.

Five years later, how many of the six remain? Has the CIA eliminated them all? Probably, now that relations with Vietnam are restored. But the question of who these deserters and defectors were remains a mystery -- as do the methods the U.S. government used to ensure they would remain invisible.