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It’s a sunny afternoon in mid-May, and P Street Beach, a rolling meadow in Rock Creek Park west of Dupont Circle, could not be more laid back. Sunbathers lounge on blankets and towels on the slope. A woman walks her dog through the park’s tall grass. A couple sits in the shade, eating lunch.

But not everybody down at the beach is punched out. Darting among the trees and sunbathers, 40-year-old Chab Dunn is on the case. Dunn is not a cop or a park ranger, just a country boy in the big city who’s had enough. Call him a concerned citizen—extremely concerned.

Dunn may not be licensed, but he’s armed and ready for any trouble that might come his way. A shiny whistle dangles from his neck, a camera is concealed in his red-white-and-blue moneybag, and the pager on his belt is actually a double-barreled mace-spray device. These are essential weapons in Dunn’s 14-year crusade: to rid his Dupont Circle neighborhood of panhandlers, drunks, petty crime, littering, loitering, and just about any other unseemly aspect of downtown life. While he claims to have formed and joined various groups to push his agenda, Dunn’s hard-core vigilante MO makes him an odd man out.

“[The neighborhood] has been going downhill since I’ve been here,” says Dunn. “Nobody was taking control—everybody was passing the buck—so I felt like I had to do something.’’

There’s no illegal activity in sight, so for now Dunn works the litter beat. With a baseball cap topping shoulder-length hair, he swaggers hurriedly down the trash-strewn pathway. His cowboy boots crunch on broken glass as he picks up empty liquor bottles, pausing only to cram dripping armfuls into a garbage container already overflowing from recent patrols. Satisfied, Dunn points to a spot behind a stone wall on a muddy bank above the creek. It was there that he helped cops catch a robbery suspect, he says. The fleeing crook tried to duck into the underbrush, but Dunn—with the aid of his high-power flashlight—flushed him out of his hiding place. “He made the mistake of coming into my park,’’ he says, chomping on coffee beans for extra energy. “This is my turf.’’

Then, letting loose a wild, screeching call to the squirrels, Dunn takes off down the winding trail into the woods.

The park and the surrounding neighborhood make up the adopted domain of Dunn, who claims the “b’’ in Chab stands for “bad boy.’’ When he’s on patrol, though, he goes by the street name “Duke.’’ He mentions an old movie in which John Wayne and his troops battle for the Normandy beach, then he gestures toward the P Street Beach: “This is my Normandy. This beach is a national public park, and it deserves respect. And we need everybody to be more considerate, and not be trashing and not be drinking and not be cracking—and no nudity.’’

On this afternoon, the park seems the picture of tranquility, but Dunn warns that it’s a mirage: At night, the place becomes a den of iniquity, a haven for muggings, public drunkenness, and sexual trysts. The police don’t have the manpower to monitor the park, so he’s decided to do it himself.

Dunn takes his obsession not only to the streets, but to the District government. At a Ward 3 town meeting this spring, Dunn laced into Mayor Marion Barry for ignoring the “safety and security’’ of the city. Clutching a passel of brochures for grass-roots organizations and shouting into the mike, Dunn stunned the audience and Barry with a furious barrage of invective.

“I’m a prime example of a small businessman who’s fed up,” railed Dunn. “See my hat? That’s PACT-CEP, that’s Police and Citizens Together….I’ve been on the beat, I’m also a block captain, I’m also with the Fraternal Order of Police, I’m also one of the new [volunteer] park rangers, and I’m also going to join the Police Emerald City—that’s the Irish police.’’ Even for the no-holds-barred demiworld of D.C. politics, Dunn’s performance was startlingly explosive—and it unsettled the usually unflappable mayor, who couldn’t get Dunn to shut up.

In a futile attempt to dismiss the raging Dunn, Barry at one point suggested, “You oughta join the police reserve….Since you’re a park ranger and you’re this and that.’’

Dunn glared at the mayor and shot back: “I’M NOT JOINING!’’

Dunn continued hammering away on public safety themes until jeering from the crowd of 200 forced him away from the mike.

“I’m just a blunt country boy speaking his mind,’’ says Dunn, a native of Virginia’s Eastern Shore. “I’ve got an attitude you might say. I’ve been giving ’em hell for a while, and I won’t stop ’til we win the battle.’’

Equal parts Travis Bickle and Serpico, Dunn has his supporters: “Chab is someone who is very impatient with the slow pace of government to solve problems,’’ says Edward Grandis of the Dupont Circle Merchants and Professionals Association. “So he’s a little bit of the Wild West, saying, ‘I’ll try to solve them myself.’ Certainly the business community is appreciative of his efforts.’’

When he’s not on patrol or causing a ruckus at community meetings, Dunn hangs out in the cozy basement confines of his P Street photography studio, blasting country music and developing images of a crime-plagued world. Though he remains a professional shutterbug—his studio is decorated with photos of Washington luminaries from President Clinton to Lynda “Wonder Woman” Carter (who signed her portrait, “To Chab with Love!”)—Dunn gets most fired up by the pictures he shoots when he’s not on the clock.

His extensive archive includes snapshots of tattered beggars, homeless people lying on sidewalks, vandalized shops, and piss-stained alleyways. Sometimes he shows the photos to police as evidence in an investigation, he says, but mostly they serve as a record of the neighborhood’s decay.

“I’ve been documenting this area since ’82,’’ says Dunn of his extensive archive. “I’ve been spit on, cussed out, and abused. I’ve had my life threatened so many times I’ve lost count.’’

Snapping candids of street people isn’t an easy thing to do, especially when Dunn is ordering vagrants to scat from a store entrance or when he’s calling the police on those too drunk or stubborn to listen.

“Chab’s putting himself in harm’s way—these assholes out here will cut his throat one day,’’ says Greg Shelton, a former D.C. policeman and longtime Dupont Circle resident. “I thought he was a nutty for a while, but he’s done more work out here than any 10 cops put together. He’s trying to do the police’s job without the weapons and without anybody backing him up. He’s a leper.’’

“Chab’s done a lot of good, and things are a lot better,” says Lt. Patrick Burke of the Metropolitan Police Department, who has toured the neighborhood’s trouble spots with Dunn in his cruiser. “He’s fiery, and he’s a little wild, but we need more people like him who have the balls to get involved,” Burke says.

On the streets, Dunn says he is careful to distinguish between criminals and innocuous homeless folks. On his P Street beat, he approaches T.C., a Vietnam vet who often stops traffic by urinating on the street, and helps him make a call on a pay phone to a lawyer. He also deals regularly with “Black Moses,’’ another Dupont Circle fixture. As Dunn passes in greeting, he stuffs a dollar bill into the man’s pocket: “We’ve weeded out a lot of the hustlers, and now we’re down to the nitty-gritty homeless who really need help. I’m not just cracking down without giving assistance. That’s why I’m starting the SOS-PACT, so they have a number to call to get help.”

Dunn explains that SOS-PACT (emblazoned on one of his many baseball caps) combines the international distress symbol with the Police and Citizens Together group he’s worked with for years.

“Everybody should say, ‘Hey! Wake up!’ When you see something that’s suspicious or out of hand, report it,’’ he says. “Everybody needs to stop saying, ‘It’s not affecting me—it’s not my problem,’ because it is their problem—it’s everybody’s problem.’’

Then Chab “Duke’’ Dunn spots a man sprawled across the sidewalk. Passers-by simply step over or walk around the stretched-out, inert body, but Dunn knows it’s a regular—a drunk who’s sleeping off a bottle or two—and he sprints to the scene.—Eddie Dean