Now, to the big business of shoplifting. It's not just a problem for the stores. It's affecting you, too. Tonight, we're undercover as police prepare to bring down one highly-organized shoplifting... See More
Now, to the big business of shoplifting. It's not just a problem for the stores. It's affecting you, too. Tonight, we're undercover as police prepare to bring down one highly-organized shoplifting ring and the woman they believe could be the key to it all. Here's ABC's Matt Gutman. Reporter: It's a $13 billion epidemic. Shoplifters across America are costing $35 million a day to retailers. And the Numbers keep growing. As seen on these youtube flash mob videos, many are brazen enough to steal anything and everything. But while shoplifting out in the open is one way to do it, down in Polk county, Florida, there's a more sophisticated method. What you're watching investigators say is an organized shoplifting ring in action. In this case, the suspect, Melinda Ford, is about to hit the dressing room at bell's department store in Florida. Our main target in the store. Reporter: Last year, we were given access to an unfolding investigation, to a crime that starts with sleight of hand and ends up costing all of us big money. Cops tell us they are the prime suspect. They call her the booster. And they believe she could be the key to bringing down a multilayered Florida shoplifting ring. We have one occupant and one suspect. Reporter: That's why sergeant Jim ostojic from the Polk county sheriff's office, has spent a month chasing puffy, as she moves from store-to-store. We're in hot pursuit right now. Westbound on I-4. Reporter: Not exactly sure where she's going. But we're following. Other the last three years, shoplifting has become a growing national problem. Stores mark up merchandise to offset the losses. And it will cost your household roughly $400 a year. Sounds like they're headed to Adel's. Reporter: The woman driving puffy around in the yellow beetle -- they call her peewee. We're blurring her face because she's a police informant. She is to enter the fitting room with two of everything. And once inside, conceal one of each item under her street clothes. Peewee tells the cops that puffy hands the items over to a network of men and women she pays to return the goods to the store. We watched as bell security monitored what they say was one of the illegal returns going down. He just returned the stolen stuff. Reporter: Suspected returners cash the stolen goods in for store credits in the form of gift cards. They believe the gift cards will turn up on popular online auction sites. The gift cards are like money, yes? They're like gold. Reporter: After weeks of following puffy in and out of stores along a 90-mile stretch from Orlando all the way to Tampa, sarge and his team are finally ready to arrest her. Investigators say if they can flip puffy, they're betting they can round up the returner, and bring down the whole booster ring. Bell's security team is in place. They're inside the store, monitoring puffy and the police informant peewee on surveillance cameras. And radioing their movements to officers outside waiting in the parking lot. Suspects are exiting the store. Reporter: Unmarked police car is waiting. As they exit the parking lot, the police pull up behind them. Peewee who has been wearing a wire for weeks, fakes being terrifying. They coming. They coming. Oh. Reporter: This particular bell's is right across the street from their own sheriff substation. So, they pull over puffy and peewee right into the station's parking lot. Puffy is escorted inside. Directly into an interrogation room. They need to turn puffy because they believe as the head of the ring, she's the only one who can lead them to everyone involved. I want to get one thing straight with you, okay? Understa understand, if you're going to cooperate with us, you have to fully cooperate. If you don't want to do that, you need to tell me now. Reporter: The rest of the suspected accomplices likely don't know who each other are. I want to name everyone who could set up a deal today. Reporter: After a few hours confronting her, police say puffy finally seems to crack. These guys have flipped puffy. And they've managed to call everybody in her virtual roll decks. She's going to talk to them. Reporter: Over the next 24 hours, puffy works and works well for the police. He would be the only person. But he don't have her phone number. Reporter: Methodically helping them set up and round up her alleged accomplices. As she sets up to bust them, she seems surprised that what she's been doing is considered a serious crime. I never thought that what I did was this serious. It's very serious. Actually is organized crime. Reporter: Puffy, who will later receive a two-year prison term plus ten years of probation, gets to work, helping to round up dozens of suspected returners. Picking up one of the other suspects right now. Black shirt on, red pants. Going right for it. Reporter: These are the people that puffy claims she paid to return the stolen merchandise. Police say they have evidence that 33-year-old Erica is also one of them. She would later plead guilty and was given 24 months of probation. I don't want them in my face. Reporter: Police say Erica only made about 5 bucks or 10 bucks for each return. Next, the suspected Venters. They're the people that puffy tell us buy the gift cards from her for about 50 cents on the dollar. We have a warrant for your arrest. Reporter: One of them sells her merchandise at a neighborhood store. They send her in with dresses they secretly marked. I've been stealing all damn day. I'm going to go back to the store. Reporter: Police have coached puffy to tell bubba, that the items are stolen. All right. I'm not going to argue with you. It's stolen. Reporter: The next day, the police raid the store. Polk county sheriff's search warrant. Reporter: And find most of the merchandise up for sale. I didn't know it was stolen. I want you to remember something, okay. Keep in mind that your store is videoed and audio recorded. Yes. When she told me, I didn't know what's going on. So, it's got to be responsible for my actions. Yes, sir. Reporter: He was later convicted of dealing in stolen property and sentenced to 36th months in prison. Anytime that you have any idea that we were following you? Nope. Never in a million years. Reporter: In the three weeks we followed them, the Polk county sheriff's office arrested puffy and 16 of her suspected associates. And were able to stop what they say is one of the largest organized retail crime rings operating in central Florida. For "Nightline," I'm Matt Gutman, in Lakeland, Florida.
This transcript has been automatically generated and may not be 100% accurate.