In Louisiana, a man duped the governor into believing he was the lone survivor of a Navy SEAL team ambushed in Afghanistan. In California, a jousting promoter said he was a SEAL veteran, not just a veteran of battles at Renaissance fairs. And in Georgia, a televangelist listed a stint with the SEALs in his online bio for years, along with bit parts in the films “Green Lantern” and “Who’s Your Caddy?”

None of these men ever served in the elite Navy units that undergo some of the toughest training in the military and undertake some of its most dangerous Special Forces missions. And while there have always been SEAL impostors, their ranks have been reinforced since a SEAL unit based in Little Creek, Va., killed Osama bin Laden six weeks ago.

“I’ve told four women alone this week to run the other direction,” said Mary Schantag, who, along with her husband, Chuck, a disabled veteran, checks out potential impostors and posts their names on their Web site, the P.O.W. Network.

The claims surface as stray comments in bars, a line in a Facebook profile, or an insignia worn on a cap. The consequences are often nil. Pentagon officials have said they don’t have the resources to fact-check every potential liar.

So the only thing standing between SEAL impostors and the truth is a small band of veterans and civilian volunteers, scattered across the country, who have made it their life’s work to expose phonies in all aspects of military service, including bogus war medal recipients.

“Only 500 [SEALs] served in Vietnam. And we’ve met all 20,000 of them,” said Steve Robinson, a former SEAL in Forsyth, Mo., and author of “No Guts, No Glory: Unmasking Navy SEAL Imposters.”

When news of bin Laden’s death broke, these investigators say, they were soon overwhelmed by reports of suspected SEAL phonies. Robinson, who had hunted fake SEALs for 10 years, was called out of self-imposed retirement to help fellow volunteers track down claims.

Military service impostors can go to extraordinary lengths to bolster their lies. A West Virginia man recently went to his grave saying he had won a Purple Heart, a Distinguished Service Cross and a Silver Star — and had news clips from the 1940s to prove it. But when Doug Sterner of Alexandria, a decorated Vietnam War veteran and war hero boast-buster, began digging around in March and obtained the man’s service records, he found a note from 1945 inserted by an officer that said the man’s medal claims were bogus.

As is often the case with such posthumous discoveries, the news did not go over well with the man’s family.

“If they saw me on the street, they would punch me out,” Sterner said.

The Defense Department has so far declined to make verifying war hero claims easier by centralizing records across the services. At the Washington Navy Yard, for example, the names of recipients of all Navy awards sit in boxes, recorded on 3-by-5 index cards.

SEAL impostors are among the easiest to catch. With a few clicks, their names can be run through a comprehensive and regularly updated database of all men who trained and served with the Naval Special Warfare units, which include the SEALs and their precursor units, from the end of World War II to the present day. (SEAL is an acronym for sea, air and land; members are part of the Naval Special Warfare Command, based in Coronado, Calif.)

Robinson estimates there are only 7,000 living former SEALs and 2,200 on active duty. By his calculations, the odds of running into someone who has played in the NFL are better than the odds of meeting a current or former SEAL.

Saying you’re an ex-SEAL might get you a free dinner down at the VFW lodge or overcome a woman’s better judgment, but other fakers are out to defraud the Department of Veterans Affairs. (A 2007 sting in the Northwestern states by the VA inspector general uncovered various military impostors who VA said defrauded the agency out of $1.4 million in benefits.)

Others still are people with legitimate accomplishments — doctors, engineers, police officers and preachers — who can’t resist the urge to embellish.

Celebrity fitness trainer Carter Hays was already established in his field when he started claiming to be an ex-SEAL four years ago. He did it, he said, to “fill a hole in my character.”

Hays had actually served in the Army in the ’70s, was a combat medic and had wanted to join Special Forces but never did.

“When you have something missing in your heart, and if you don’t fill it with Christ, you will fill it with what is accessable [sic] at the time or moment,” he said in an e-mail. “I never intended it to be ‘public.’ Just a few friends.”

But Hays’s claims did become public when he trained several participants on the “Biggest Loser” TV show. His SEAL claim, which he circulated on the Web, caught the attention of ex-SEAL Don Shipley of Chesapeake, Va., who specializes in outing phony SEALs. Shipley made Hays the subject of one of his “Phony Navy SEAL of the Week” YouTube videos, in which he excoriates poseurs.

“I made a terrible mistake that I am ashamed for,” Hays said in an e-mail to The Post.

Once in a rare while, impostors get hauled into court. It’s illegal under federal law to impersonate a member of the military or to wear unearned military honors. But few perpetrators are prosecuted. Clever impostors found a way around the law by showing off their medals without wearing them. The Stolen Valor Act of 2005, which tried to close that loophole by outlawing verbal and written claims, set off a court battle over whether liars are merely exercising their right to free speech.

The outcome is likely to affect what will happen to Ronnie Robbins, a southwest Virginia man who last month was convicted for lying about being awarded two medals for valor in Vietnam and defrauding the Department of Veterans Affairs. He faces up to 28 years in prison plus fines.

Once confronted, most impostors typically deny their lies, the boast-busters say. But a tiny minority fess up in hopes of redemption.

Elton B. Murphy came clean in 2002 after being outed by a now-defunct verification service called AuthentiSEAL. He started lying about being a SEAL not long after he washed out of SEALs training in the 1980s, and kept it up for 16 years.

“I led certain individuals to believe I was a NAVY SEAL,” reads his apology letter posted on the POWNetwork.org site. “At least one individual I did try to convince I went on missions in Central America.”

He apologized to the SEALs. He apologized to the Hillsborough County sheriff’s department in Florida. (He once claimed he was attacked by masked men at gunpoint.) He apologized to his family. He left out only a few other misdeeds “of personal nature . . . in the ramance [sic] area and marital area of my life.”

He signed the letter simply: “Elton B. Murphy LIAR.”