The nearly 300 Nigerian schoolgirls kidnapped last month from their boarding school in Chibok by the Islamist militant group Boko Haram are suspected to be deep in Nigeria's northeastern Sambisa Forest, officially a game reserve but long a redoubt for smugglers and criminals hiding in its dense and thorny scrub.

With the region's remote landscape and unprotected borders, many fear that at least some of the girls may have been dispersed to neighboring Chad and Cameroon, either to other militants or into the global marketplace of children destined for every manner of work, from domestic or agricultural labor to sexual exploitation, forced begging, and child soldiering.

"I abducted your girls," said the smiling Boko Haram leader, Abubakar Shekau,