Editor's note: Watch an update on the investigation into Craigslist's adult services section on AC360 tonight at 10 p.m. ET.
Steve Turnham and Amber Lyon
CNN Special Investigations Unit
On a late afternoon in early June, undercover police officers circled a one-story highway motel north of Washington. Inside was a 12-year-old girl who told her mother she was being forced to work as a prostitute.
According to her mother, the girl had started running away from home earlier this year. She found out her daughter was in the sex trade when she saw her in an adult online classified ad. The girl was advertising herself as a 24-year-old with a bogus name. The next time she ran away, her mother reported her missing.
According to police and anti-trafficking advocates, the internet has now become the preferred way to sell women for sex. It's fast and convenient for the pimps and relatively safe for the men who pay for sex. Instead of trolling the streets, they can now look through hundreds of girls from the safety of their homes or hotels.
This time, the girl was lucky. She called home, and the call was traced to a Knight's Inn in Laurel, Maryland, where police were quickly on the scene. They rescued the girl and arrested a 42-year-old man and charged him with human trafficking.
Of all the sites that offer "adult services," Craigslist is one of the most popular. The online classified ad site is used regularly by about 50 million Americans for everything from buying used lawn furniture to finding a job or a roommate.
It's also used to sell sex, making Craigslist a prime target of a nationwide campaign against internet prostitution.
"Most of the young women we've worked with who have been exploited online talk about Craigslist," said Andrea Powell of the anti-trafficking group The FAIR Fund. "Craigslist is like the Wal-Mart of online sex trafficking right now in this country."
According to police who investigated the case of the missing 12-year-old, she had previously advertised on Craigslist under a false name and age. Craigslist declined to provide copies of the ad, citing privacy concerns.
Craigslist founder Craig Newmark defended his site, saying it is doing more than any other site that hosts adult ads to help filter out underage prostitutes and report them to police.
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