Sex tourists tend to hail from affluent countries, including the West, South Korea, Japan and China, but research suggests Cambodian men remain the main exploiters of child prostitutes in their country.
The local sex industry sweeps up both children from the neighborhood -- sold, like Kieu, by their parents – as well as children trafficked in from the countryside, or across the border from Vietnam.
"We didn't believe it until we saw vanload after vanload of kids." Weak law enforcement, corruption, grinding poverty and the fractured social institutions left by the country's turbulent recent history have helped earn Cambodia an unwelcome reputation for child trafficking, say experts.
"It's not that she was stolen from her mother -- her mother gave the keys to the people to rape her." Brewster, a former pastor, moved from California to Cambodia with wife Bridget in 2009, after a harrowing investigative mission trip to the neighborhood where Kieu grew up -- Svay Pak, the epicenter of child trafficking in the Southeast Asian nation.
"Svay Pak is known around the world as a place where pedophiles come to get little girls," says Brewster, whose organization, Agape International Missions (AIM), has girls as young as four in its care, rescued from traffickers and undergoing rehabilitation in its safehouses.
But the majority of sexual exploitation of children is of adolescents, and that's taking place in commercial sex venues." The abusers would often be local, situational offenders, he says.
Research suggests some of the Asian perpetrators are "virginity seekers," for whom health-related beliefs around the supposedly restorative or protective qualities of virgins factor into their interest in child sex.
As one of the most disadvantaged neighborhoods in one of Asia's poorest countries – nearly half the population lives on less than per day -- the poverty in the settlement is overwhelming.
The residents are mostly undocumented Vietnamese migrants, many of whom live in ramshackle houseboats on the murky Tonle Sap River, eking out a living farming fish in nets tethered to their homes. The river is fickle, the tarp-covered houseboats fragile.
Like other local mothers CNN spoke to, she blames poverty for her decision to sell her daughter, saying a financial crisis drove her into the clutches of the traffickers who make their livelihoods preying on Cambodian children.