Brenda Lee, a security manager at the downtown Woodward & Lothrop store, runs up two escalators and squeezes past Christmas shoppers while listening to walkie-talkie crackle about a shoplifting suspect who demands to return a stolen red dress for a $40 cash refund.

As Lee leaps off the top escalator, her eyes zoom in on the target. Then she quickly ducks behind a rack of plaid skirts.

To make an arrest, Lee must witness the transaction; she shoves her walkie-talkie into her jacket and fades undercover. Her heart pounds, and she tenses. She is a cat twitching after a mouse, ears pricked.

"When I get a radio call, I'm like a hunter," she said. "I'm just dead into it: going. It's almost like I'm stalking something."

But, wait -- the suspect waves a sales receipt for the red dress. Lee can't chance a false arrest. As the clerk rings up the $40 refund and the suspect turns towards the designer shoe department, Lee moves in to check the receipt.

Incredibly, in the second that it takes Lee to verify that the receipt is a fake, the shoplifter has vanished from designer shoes. Gone, disappeared into the holiday crowds. Lee holds her head in her hands.

"I'm going to delete this case from my mind," she said. But, five minutes later, the blown case of the red dress still torments her. "This makes me so mad . . . it makes me so mad to lose this case."

While the back-to-school season has the biggest shoplifting losses, the winter stretch from Thanksgiving to New Year's runs a close second. Woodies won't release statistics, but The Greater Washington Board of Trade estimates the area's retail losses to theft totaled $460 million for the 12-month period that ended in July.

The store where Lee works, at 11th and F streets NW, is sprinkled with television monitors. A mannequin, nicknamed "Hildegarde," watches over the J.G. Hook and Evan Picone sportswear collections through a camera implanted in her left eye. Fitting rooms are locked, and clothes often are wired together.

But thieves are swift, they are cunning, and they sometimes slip by. Nobody knows this better than Lee, whose job it is to catch them. "It keeps your brain going all the time," she said.

Lee grew up in a tiny North Carolina town, in a place so small that she had never heard of Martin Luther King until she moved to Washington in the 1960s and had to ask what all the burning and rioting was about. Shoplifting was not anything she had ever given much thought to, either.

"When I first started there, I used to come home and say to my husband, 'God, honey, we caught this girl today, and she had all this stuff tucked between her legs. And we had this guy, and he was fighting us all over the place.' "

So amazed was she that the stories kept pouring forth: about women cramming stolen merchandise into girdles, about the man who grabbed 23 pairs of pants in a "door hit" and ran for the nearest exit. Finally, her husband told her: "Brenda, enough of Woodies and that security department."

But even after nine years on the security beat, her enthusiasm for what she does is hard to dampen, and she easily slips into the tale of how she wrestled one shoplifter into submission in a Woodies bathroom stall.

"She stole a black suit," Lee said. "I'll never forget it."

Lee's is a job that requires the mind of a cop and the stealth of a burglar. Fitting rooms are not under surveillance, but she has been known to creep up outside them, listening for the telltale sounds that electronic sensor tags are being popped off clothing.

She also crouches for hours in hidden observation posts that are disguised from the outside to resemble heating vents or mirrors. There, she scans her turf for shoplifters the way duck hunters watch for incoming birds.

"Nine times out of ten, you can sit up there and they'll come to you," she said.

But her favorite activity is patrolling the floor, undercover.

She tries to pretend that she is a Woodies customer, with $100 to spend.

What would she buy? Always, she watches for suspicious behavior: the man who darts behind a secluded rack, the woman whose head bobs up and down as she crams stolen sweaters into a bag.

"I should have written a book about it a long time ago," said Lee. "About patrolling the floor and looking for thieves. I hate thieves. I hate 'em. No, I don't hate them. I dislike them. I smile every time I make an arrest."

Bulky coats and empty shopping bags activate her inner alarm, and while she has never seen anybody try to pass off stolen merchandise as a pregnancy, nothing would surprise her. Her most intriguing case to date, she said, concerned a woman who went into the fitting room with 10 dresses and reappeared empty-handed.

"My heart is beating. We go into the security office, and I read her her rights," Lee related. "Then I start to pat her down. Nothing around her neck. Nothing even around her middle. I thought she might have put them in a girdle, built up in back, but nothing there, either. I'm thinking, where can these dresses be?

"So, I start moving down one leg. I get to the ankle of one leg, and there was this knot. This big knot. She had tied five dresses around the ankle of one leg, and she had four around the other."

The woman had stuffed the dresses in socks, hidden by large bell-bottom jeans.

Over the years, Lee's attitude has changed. Busting shoplifters used to depress her.

"I just hated to see those kids going to jail," she explained. She still can empathize.

"These people sometimes steal out of need," Lee said. "They do it because they don't have the money, or they need to buy drugs, or food for their kids. So I do not jump up and down and say, 'Let's go have a drink on this shoplifter.' "

But now she views her efforts as helping people, not only the regular store customers who bear the cost of shoplifting losses, but the thieves themselves. Shoplifters tend to steal until they get caught. And Lee offers her own version ("It's my counseling service") to suspects locked in handcuffs, waiting for squad cars.

"I've caught girls aged 14 or 15," Lee said, "and I'll tell them how they can do positive things instead of using their minds to steal. 'Why don't you join one of the police boys and girls clubs, and get involved in sports?' I'll say."

Lee volunteers time to one such club, and once brought 10 girls into Woodies to see her nab a shoplifter.

"I do think it made a big, big impression on them," she said.

Sometimes, she hears from those she has counseled. When one girl Lee had busted for stealing a $44 skirt returned after a jail stay to thank her and to say that her days of thievery were over, "I don't even know what the word is, but it's got to be the biggest word in the vocabulary to describe how I felt," Lee said.

Over the years, Lee has dispensed so much advice that catching shoplifters and helping discouraged city residents get back on track have become almost synonymous in her mind. Which is why she sounded thrilled when she spoke of a recent arrest -- a good bust -- that she had made in the juniors department.

Lee had perched on a stool behind the heating vent. She could look out the metal slits, and see the racks of clothes.

"All of a sudden, I see this girl's head go bobbling up and down," Lee said. "When she came up, she was looking around. And you could see a hand motion, like she was pushing something down into a bag."

All the familiar feelings came back: the pounding heart, the huntress after the hunted. When the girl left with a bulging shopping bag of stolen goods, Lee jumped out of her hiding spot and tracked her through menswear.

She arrested the girl at the subway entrance to the store.

"I felt very happy," Lee said.