It's a question that keeps me up at night.

Activists say the international community has done relatively little to pressure Mauritania to address slavery. "The French government and American government have had a lot of opportunities to help Mauritania step up and deal with this -- and have pretty much squandered those opportunities," says Kevin Bales, of Free the Slaves. People tend to focus on topics like child trafficking and sex slavery, says Sarah Mathewson, Africa program coordinator at Anti-Slavery International, rather than the old-world slavery in Mauritania.

The U.S. ambassador to Mauritania, Jo Ellen Powell, called slavery in the country "completely unacceptable and abhorrent" and said America is pressuring Mauritania to change. The nation should invest in the education of its children rather than "keeping them sweeping floors somewhere or herding goats," she said. "Human capital development is something that's very important to the Mauritanians and I hope that they get that connection."

For a few weeks after returning home, I tried to block the most troubling images from my mind: haunting villages where kids eat sand; a slave owner who smiled while he told us about the free labor he gets from people with darker skin; and, most of all, the piercing eyes of a woman whose master left her infant in the sand to die.

Mauritania is a place of agonizing beauty, one that's hard not to love and curse. Its people have lived with unfulfilled potential and broken promises for decades, since the country first tried to abolish slavery in 1905. But that could change, several activists told us, if Mauritania knew the rest of the world was watching.

The United Nations has proposed a number of changes the Mauritanian government could make to quicken the end of slavery. Among them: Pay lawyers to represent victims; allow international monitors into the country to conduct a full survey of slavery; and fund centers like the one SOS runs to rehabilitate slaves who have claimed their freedom.

It would help if a global public demanded these changes. "It's a destitute country," says Kevin Bales. "It needs a few friends in the world."

Perhaps then women like Moulkheir and Selek'ha could find justice.

And Boubacar and Abdel could get their wish.

We asked the SOS founders how they will know when their fight against slavery in Mauritania is over -- how they'll know they have won. Both men had the same answer:

When a former slave becomes president.

How this story was reported: CNN's John D. Sutter and Edythe McNamee traveled to Mauritania for eight days in December 2011 to witness slavery first-hand. Scenes of Moulkheir Mint Yarba's escape from slavery are reconstructed based on interviews with those involved, written and video testimonies given to abolitionists at the time of her escape and legal documents provided by SOS Slaves. CNN could not confront the men who allegedly enslaved Moulkheir. Their names have been omitted for this reason. Most interviews were conducted through a local translator, who spoke English, French and Hassaniya, a dialect of Arabic. The translator, who did not want his name used for security reasons, also conducted followup interviews on CNN's behalf.