Who killed 5-year-old Shaniya Davis? Her mother is charged with human trafficking, and many questions remain about what happened. Watch "Nancy Grace" as she digs deeper, tonight at 8 on HLN.
(CNN) -- It sounds like the plot of a crime drama or the scourge of a developing country, but human trafficking is a serious problem in the U.S. and America's children are frequent pawns, experts say.
The case of Antoinette Nicole Davis, a North Carolina mother accused of selling her 5-year-old daughter, Shaniya, into prostitution, highlights one of the most heinous -- albeit rare -- forms of trafficking within the U.S.
Davis faces numerous charges, including human trafficking, felony child abuse and prostitution. Mario Andrette McNeill has been charged with kidnapping in the case after police said a surveillance camera captured images of him and Shaniya at a hotel in Sanford.
Polaris Project, a nonprofit organization that studies human trafficking, has more frequently seen cases in which children were sold by family members "out of desperation in developing countries" such as Cambodia or sub-Saharan African nations, said executive director and CEO Mark Lagon.
"But it happens sometimes here," he said.
More common in the United States are traffickers who exploit abused runaways or so-called "throwaways" -- children abandoned by their parents and living on the streets, Lagon said.
"The trafficker plays the role of a father or loverboy who is offering care to the child, who is vulnerable," he said, explaining that what begins as flattery and attention often turns to suggestions of prostitution.
The child, typically homeless and in need of food and shelter, can be manipulated into "survival sex," Lagon said. In other instances, the trafficker or pimp will get the child hooked on drugs and use their addiction as leverage.
Named for the North Star that guided slaves along the Underground Railroad, Polaris Project works to stamp out the global trade in humans.
Lagon, formerly the State Department's director of the Office to Monitor and Combat Trafficking in Persons, said it's a tough fight because there is a dearth of "good statistics" on human trafficking and it's not a crime in which victims readily come forward.
But the news is replete with reports on major rings being busted. The FBI did not return messages to discuss human trafficking, but news releases from the agency's Innocence Lost initiative show that in the past 18 months, four stings -- dubbed Operations Cross Country I, II, III and IV -- have yielded about 2,300 arrests and the recovery of about 170 children.
"We may not be able to return their innocence, but we can remove them from this cycle of abuse and violence," FBI Director Robert Mueller said in a statement after a February bust.
Specific examples also abound. In August, two bar owners and a manager in Long Island, New York, were charged with sex trafficking and alien harboring with victims as young as 17. A few days later, a husband and wife in Orange County, Florida, were charged with kidnapping a 15-year-old at gunpoint and forcing her to turn tricks.
In September, a U.S. Army private and three other men were indicted on charges of running a sex-trafficking businesses from a Millersville, Maryland, apartment. One of the prostitutes was 16.
No pleas have been entered in the Florida or Maryland cases. The three defendants in Long Island have pleaded not guilty.
While prostitution is a common impetus for trafficking children, Lagon said there are numerous examples of young men and women being forced into domestic servitude. Many times, he said, those victims are sexually abused as well.
Though statistics on the depth of domestic trafficking are difficult to ascertain, the University of Pennsylvania conducted a study in 2001 showing that between 244,000 and 325,000 American children were at risk of sexual exploitation, including child pornography, juvenile prostitution and trafficking children for sexual purposes.
The average age of a female victim's first involvement in prostitution, according to the study, was between 12 and 14.
"That, shockingly, means a number get in when they're incredibly young, and that's all the more horrifying," Lagon said.
Lagon said he was impressed with federal initiatives and believes "it's great the FBI has more and more focused on trying to save prostituted children as sex trafficking victims."
The only caveat to his praise, he said, is a concern that adults swept up in raids are sometimes charged as prostitutes when they, too, may have been subjected to coercion or pulled into the trade as minors.
The onus is on society and government to stop the trafficking of American children, he said. Citizens should pay attention to signals that something is amiss with a child and be careful not to "sneer or stigmatize" when they see a prostituted teen.
Government, meanwhile, should toughen its punishments for child trafficking and more actively target the "johns" and pimps who make the trade possible, according to Lagon.
"That person has to be punished like they've committed a crime akin to slavery. This is something that deserves decades in prison," he said.