The day’s first lead arrives in Anthony Anderson’s inbox mid-morning. The tipster says a man claiming to have served in Vietnam with Charles Beckwith, the late founder of the Army’s elite Delta Force, is using that association to sell his training skills to police departments. His story might well be true. But boasts like these fire Anderson’s suspicions.

From a laptop at his kitchen table, in a quiet subdivision outside Columbia, South Carolina, Anderson investigates a particular form of lying that’s come to be known as stolen valor: civilians fibbing about military service, and veterans embellishing their records with bogus claims of battlefield medals and missions with elite units. Fueled by coffee and Coke, he goes about unmasking imposters as a detective might, digging through public records and compiling dossiers. His computer dings with Facebook messages and his phone buzzes with texts, many of them from a loose network of self-styled investigators, mostly veterans themselves, scattered across the country.

Anderson, a staff sergeant on active duty in the South Carolina National Guard, has been doing this work of his own initiative and on his own time for several years. Not long after returning from Afghanistan, where he was deployed from 2009 to 2010, he started the Stolen Valor Facebook page, then the Guardian of Valor website, which features a rogue’s gallery of hucksters and fraudsters. The site’s traffic ballooned in 2013, when Anderson helped investigate Matt Farmer, a former soldier and contestant on American Idol. Before Farmer’s audition, in which he performed a Sam Cooke song, he told the judges that an IED explosion in Iraq had left him with a traumatic brain injury. But though Farmer had served in Iraq, he hadn’t been injured. “My inbox started lighting up with guys who had served with him,” Anderson told me, as he tapped out a text message regarding one of his half-dozen current investigations.

Anderson keeps his dark hair trimmed short on the sides, and on the day I visited him, he wore blue jeans and a black T‑shirt emblazoned with u.s. veteran. He comes across as steady and unexcitable, his thick eyebrows framing a calm gaze. Doug Sterner, who served as a combat engineer in Vietnam and mentored Anderson in imposter investigation, describes him as circumspect. “He has a levelheaded approach,” Sterner told me. “It’s not a game, you’re not a cop, and it’s not about bagging a phony. It’s about getting to the bottom of the facts.”

Sterner first discovered military fakers by accident, after launching a website devoted to cataloging the recipients of the nation’s top valor awards (the Pentagon only recently began compiling a master list). So far, he says he has compiled names and battle narratives for some 270,000 award recipients—though, as he has discovered, plenty of people claim to have received awards who never did. Sorry, Sterner learned to say when someone complained that a family member was missing from his list. Dad’s not a war hero. He finds these cases depressing, a distraction from his work “preserving the lives of real heroes,” so when Anderson reached out with a question about military records several years ago, Sterner welcomed his interest in investigating fakers; today, Sterner frequently sends stolen-valor tips Anderson’s way.

If a lead seems legit, like the one about the Special Operations soldier turned police trainer, Anderson will poke around online to learn more about the person and hopefully find a date of birth or, better yet, a Social Security number. With those, he can access military personnel records, which will show, at the very least, where and when a person served. Freedom of Information Act requests can yield more-detailed documents, like those included with discharge papers, which show war-zone duty and special awards and recognitions. Many records are stored at the National Personnel Records Center, in St. Louis, but not all. Some military branches now keep their own records, so the search process can take months. “I build the case just like I’m taking it to trial,” Anderson says. “If a jury wouldn’t look at it and decide that person’s guilty, I won’t post it.”

For as long as soldiers have gone off to war, they’ve exaggerated and lied about it, in ways big and small. When George Washington established the U.S. military’s first badges of honor, in 1782, he understood that soldiers deserved recognition, but also that they couldn’t be trusted not to embellish their exploits: “Should any who are not entitled to these honors have the insolence to assume the badges of them they shall be severely punished,” he wrote.

So it continues today. In this thank-you-for-your-service era of adulation for the military, some can’t resist the ego-stroking pull of handshakes and discounts. Others get a thrill out of putting one over on everyone else. Anderson likes to tell the story of William James Clark, whose case preceded his own investigations. In 2002, after a barge slammed into a bridge spanning the Arkansas River, killing 14 people, Clark showed up wearing an Army uniform, told authorities that he was a Special Forces captain just back from overseas, and for two days asserted that he was in charge of rescue and recovery efforts—despite the fact that he was a civilian and had never served a day. “He took over,” Anderson said, giggling and shaking his head, “because he was in uniform and they allowed him to.”

“The second you start talking about being a war hero, you have admiration from your fellow citizens. You’re a person of value,” says B. G. “Jug” Burkett, a Vietnam veteran who was the first to expose military imposters in a systematic way, and who coined the term stolen valor. Since the mid-1980s, he’s investigated about 3,000 people, outing a city-council member, the head of a Vietnam Veterans of America chapter, and a U.S. congressman. Burkett—who courted controversy himself by questioning John Kerry’s war record during his 2004 presidential bid—has also exposed hundreds of veterans who claimed disabilities from wartime service they didn’t perform and civilians who invented service records to collect disability benefits. “The types of fraud are beyond comprehension,” he says.

The 2005 Stolen Valor Act, which Doug Sterner’s wife, Pam, helped draft, made it a crime to falsely claim military decorations, but the Supreme Court overturned the law in 2012. A revised act, passed in 2013, makes it illegal to benefit financially from such lies, and several states have enacted their own statutes. But increasingly, public shaming picks up where the law leaves off. YouTube and Facebook abound with videos of veterans confronting suspected fakers on campuses and in malls, bars, and parking lots. Such efforts can border on vigilantism, and the accusers aren’t always right. (Ask Michael Delfin, a Marine Corps veteran who fought in Fallujah. Last year, two men who didn’t believe he had served jumped him in the parking lot of a Sacramento bar and broke his leg.)

Anderson condemns false accusations, noting that he attempts to contact the subjects of his investigations before posting his findings, to hear their side. He says some apologize and admit the duplicity; others stick to their stories and threaten to sue or even harm him. Some plead with him not to publish; others say they don’t care—until, that is, their name shows up in a Google search, for friends and employers alike to see. This is part of Anderson’s purpose: He wants his website and Facebook page to provide public shaming, so as to deter this sort of behavior in the first place.

When I asked Anderson whether he had greater distaste for embellishers or for civilian pretenders like William James Clark, he was quiet for a long moment. “If you served, you should know better than a civilian what it means,” he eventually said. “I’ve got a lot of friends, family members who have been wounded or killed, who have sacrificed for these awards. I have friends who have taken their own lives. So for somebody else to claim it when they haven’t earned it, it just makes you angry.”

Anderson recently started the medical-retirement process for injuries of his own, which include post-traumatic stress and a traumatic brain injury. He was due that afternoon for a medical appointment at Fort Jackson, a sprawling Army post half an hour away—a follow-up to a recent surgery, in which doctors had removed several screws used to repair damage to his sinuses and jaw. The medication he takes for his brain injury keeps him from driving, so his girlfriend, Michelle Anders, was taking him. As he settled into the passenger seat, a stack of medical records in his lap, his phone buzzed with a text from a fellow veteran: “Can you check this out?” the acquaintance wrote, sending along a URL. “He’s trying to open a veterans home and from what I hear his story on his service is bullshit.”

“It’s never-ending,” Anders said, sighing and starting the car. “He was so busy one time, I told him I was going to steal some valor just to get some attention.”