Walter Starling is running out of signs.

"Maybe it will end at 12," he says. "I only have 12 signs."

Wherever the sniper strikes, Walt Starling follows.

At a power vacuum at a Shell station in Kensington, where Lori Lewis Rivera was murdered, a roadside memorial marks the spot. Forty bouquets. Two American flags. And taped to the vacuum, one "Thou Shalt Not Kill" sign.

On the lawn behind Fitzgerald Auto Mall in nearby White Flint, where James "Sonny" Buchanan was gunned down, a note says, "Sonny, there was so much I wanted to say, so much I should have said. 'I am sorry.' May you rest in peace. K." Pinned on the same telephone pole: a "Thou Shalt Not Kill" sign.

At the Leisure World Plaza in Silver Spring - home of the Joy Luck Cafe and 99-cent hamburgers at Burger King - the glass window has been replaced at the Crisp & Juicy carryout restaurant. Salvadoran immigrant Sarah Ramos was shot and killed sitting on a park bench at 8:37 a.m. Oct. 3, the sniper's third victim on a day in which he would kill five. Flowers came soon after, as did Starling and his bold red sign.

It is here that Starling began what would become a tour of duty. This, after all, is his own neighborhood.

When he pulled up in his Jeep Cherokee, red signs and tape in the back seat, the first person he saw that day was his sister, who uses the post office at Leisure World. He does, too. So do his parents. In the faceless suburban architecture that has been the sniper's killing fields, there are human faces: mothers and sisters and old people and a woman who signed her name "K" and wanted to apologize, at last, to a man nicknamed Sonny.

Staying two, three days behind the crimes, Starling set out to follow in the footsteps of the sniper. It has been hard keeping up; the macabre scorecard keeps changing. His Jeep has logged more than 300 miles already. He started with 12 signs - which, he was delighted to learn, do not smudge in the rain.

"I don't see any difference between doing this," he says, "and visiting someone in the hospital."

Like so many people, the former radio traffic pilot from Gaithersburg has been drawn into this story. He is curious. He has theories. He feels slightly paranoid. He watches his back when he pumps gas. He notes every parked cop car along Interstate 95. He notes every passing white van. Like so many of us, Starling is affected by these crimes -except he's on a mission, part spiritual errand, part amateur investigation.

Thou shalt not kill - but someone keeps breaking the commandment. Starling wants to know who and why and, really, how. He wants to be close to the story, and putting up his red signs certainly brings Starling very close.

Just inside Washington, the intersection of Kalmia Road and Georgia Avenue is home to a 24-hour laundromat and assorted other businesses ($15.99 special on pedicures at Laura's Nails). The spot smells like the nearby China Hut restaurant. "For Pascal" says a note pinned to a pot of drenched, purple flowers. Pascal Charlot, 72, was shot dead here near the bulk-rate dry cleaners. The "Laundromat Open 24 Hours" sign is wrapped with a "Thou Shalt Not Kill" sign.

Starling was here.

And he's back to scope out where the sniper could have positioned himself. It's Tuesday, Oct. 15, nearly two weeks after the shootings began but less than 24 hours after the most recent killing. Starling - married, father of two grown kids, pilot, writer of news copy for a Washington TV station- walks about 200 yards from the crime scene. In scrub brush, Starling checks the ground for shell casings, spent beer bottles, tarot cards. He likes the spot for the shooter; it's secluded and far enough away from the intersection yet with a clear shot.

He uses his "Thou Shalt Not Kill" sign as a marker. "See it?" Red marks the spot where Pascal Charlot fell. It looks far away, but 200 yards is within range given the sniper's suspected weaponry and ammunition - a common .223 cartridge shot from a hunting or assault rifle possibly equipped with a scope. Yes, this could well be the spot, Starling believes. He gets back in his Jeep to head south into Virginia, to three more murder sites. The Jeep feels particularly safe.

What brings Starling to these scenes? A scolding, of sorts. He was at a Baltimore-Washington Methodist conference Oct. 4 in Columbia when Bishop Felton May issued a challenge. "We've lost our nerve," Starling remembers the bishop saying at the revival. He urged folks to make their own mark on the world, to put "Thou Shalt Not Kill" posters at crime scenes.

Starling thought his first stop, in his neighborhood near Leisure World, would be his last.

"I thought that would be it," he says.

But it was far from over.

Nearly two weeks later, Starling is still using his days off to follow the killer's path. After, all Starling knows the highways well; he spent 25 years as a traffic pilot. He knows exactly where he's going.

Here's his routine. Before entering any of the gas stations or businesses to ask shell-shocked employees for permission to tape scripture near their property, Starling puts on a tie because he's representing the church. He offers condolences to the business owner; no one, he says, has asked him not to put up a sign. Along with the verse from Exodus, the poster includes a toll-free number Starling hopes people will call if they need consoling. No one has.

"But the purpose of the signs is really to make a statement against violence, and for people to keep that thought in mind when they pass by," says Erik Alsgaard, a spokesman for the Baltimore-Washington Conference of the United Methodist Church.

With four signs in his back seat, Starling pulls up to a Sunoco station in Manassas, Va. The man behind the counter allows "Thou Shalt Not Kill" to be taped in the front window. A white van has been pulled over; armed men in fatigues surround it. In the median, candles, flowers and a picture of two angels mark the spot near where Dean Meyers was killed pumping gas Oct. 9.

"I feel sorry for the people who are scared," says James Gossard, whose visor reads: "Pump Your Gas For Free." Gossard, who is not a gas station employee, stands between gas pumps offering his free service. The Warrenton, Va., man is 53 - the same age Meyers was. "I figured I'd come by and work three hours," Gossard says.

Starling, meanwhile, is on the move. He crosses Sudley Road here off Interstate 66 - another exposed landscape of cater-cornered gas stations and family restaurants - the smell of Shoney's is in the air. Starling sees a spot on a ridge behind a Pep Boys sign. He tramples through the brush, again looking for shell casings or any sign of a sniper. He catches himself in the act. "I almost feel goofy doing this because I'm not a cop and never wanted to be a cop."

Down across the highway, there's the first pump at Sunoco, presumably a clear shot for an able marksman. Starling takes a photograph of the spot near the Pep Boys sign. He takes notes. He thinks he might have found the sniper's position.

"It's getting a little creepy," he says.

Back in the Jeep and on to the Fredericksburg area, in search of yet another Michael's craft store. A woman was shot in the parking lot but survived. The clerk behind the counter chokes up a bit when Starling inquires about where he can place his sign. He chooses a telephone pole by the highway.

Then, there, behind the Pizza Hut, 300 yards away, he spies another ridge. He pulls the Jeep around to the spot and searches the high ground. It would be a tougher shot from here. But remember, as Starling says, he didn't kill her.

Last stop for the day: The Exxon station where the convenience store is named "On The Run" in sunny letters. There's easy access to I-95, and the homogenous scenery includes a Waffle House, a Hooters and a Ramada Inn marquee that invites us to join them for breakfast.

At this Exxon in Fredericksburg - now, who died here? It is testimony to a heart's weariness, not coldness, that Starling is stumped. "I've lost track," he admits. After two weeks, many people are numbed by the numbers. Another shooting, a lull, and then another. The locations become a blur, too. Mobil, Sunoco, Exxon, Shell ...

Starling buys a newspaper to help him track the timeline. It was 53-year-old Kenneth Bridges who died at this gas station Oct. 11.

After taping up his sign, Starling spots the parking lot of a motel across the busy highway.

One more trip into one more set of woods to look for one more clear shot.

Like every Monday, Starling has today off. With one "Thou Shalt Not Kill" poster left in his Jeep, he plans to drive to Falls Church, Va., to the Home Depot parking lot where the sniper's ninth victim fell last Monday. Maybe Starling's next destination will be Ashland.

"It would be cowardly if I stopped," he says.

He would need more signs.