Transcript for Plain Jane Bandit
Well, tonight a reward of $10,000 is being offered for the capture of the plain jane bandit. After the mystery thieve struck seven different california banks in one month. While it may be unusual to have a woman topping l.A.'S most want the list, fbi data shows the number of female bank robbers has been on the rise in thet decade. Best way to catch a thieve, could be all in the name. Here's abc's david wright. Reporter: They call her the plain jane bandit. One of l.A.'S most wanted. Robbing more than half a dozen bank branches in the past three weeks. Without even bothering to wear a disguise. Her basic m.O., She'll approach the teller, usually she'll provide a demand note and ask for a specific amount. After that, the teller complies or sometimes they n't. Come on out, we don't want any trouble! Reporter: Ever since the untouchables took on mob barker and her gang, all the way back to bonnie and collide. I'm miss bonnie parker and this is mr. Clyde barrow. Reporter: Female ba robbers have held a special spot in american crime lower. The image of patty herst wielding a machine gun for the liberation, inspired a musical tribute. Women bank robbers are rare. It's 4 or 5% of the time that it's a woman. 20 years ago, california was the bank robbery capital of america, about seven a day on average. Now that number has dropped to just over 200 a year, but even now, according to the fbi, only 60% of the bank robbers actually get caught. So 40% of the time the bank robber gets away? It's a huge risk for the robbers. The more times they rob, that rate goes up as well, increasing the likelihood they'll get caught. So the plain jane bandit may be living on borrowed time. Ow the tellers are recognizing her. I believe by now they'll recognize her, based on the media coverage. Reporter: That's the main reason the fbi gives these folks such colorful names, hoping to make them recognizable. There's the going plaid bandit and the make it quick bandit. He keeps referencing, make it quick. There was the irreconcilable differs bandit, who cited his divorce while robbing. He recently got caught. The name, he said he hated it. He was disappointed. Reporter: Af course there's the geezer bandit who has eluded capture for years, robbing dozens of california banks in a convincing mask. The geezer bandit could be anybody, but authorities now have an important break in the case. They know where he got the mask. The company spx in van nuys specialized in high end masks. They make the mask freddie krueger wears in the nightmare on elm street movie. Criminals seem to like their masks for obvious reasons. This is the wall of shame. People have used our mask for illegal persurposes. Reporter: A chinese defector used the elder mask to board a plane in hong kong and demand asylum in canada. The puzzling thing about plain jane is she wears no mask and settles for very little money. She's not getting much money. Reporter: But still bigger than a cash withdrawal from the atm? Definitely mine. I don't know about yours. Reporter: Still we're talking hundreds of dollars, not thousands, not millions. A huge risk for a very small pay-off. At this point she'd make more money turning herself in if she could collect the reward. U.S. Bank is offering a reward up to $10,000 for the arrest and conviction of the bank robber. I think she'd want more, but she's not getting it. Reporter: The fbi is defensive about the name they've given her. She's not that plain. Reporter: But they're hoping at the rate she's robbing banks she'll soon be behind bars. I'm david wright for "nightline" in los angeles.
This transcript has been automatically generated and may not be 100% accurate.