CAZUCA, Colombia — Tawny cinder-block homes cling to the hillside in this illegal shantytown south of Bogota.

The slum of Cazuca is home to about 60,000 residents but there are few schools and no pavement, running water or other basic services. For years, the vacuum of government presence has often been filled by armed groups — paramilitary, guerilla and criminal gangs — that control the population through intimidation, extortion and violence.

Cazuca receives some of the largest numbers of displaced people in Colombia — a population estimated at more than 3 million — who flee their homes due to violence or threats. Displaced peoples are thought to make up almost half of Cazuca’s population, though exact numbers are hard to come by. Displaced peoples are hard to calculate and census counts are challenging at best in an area where most residents are considered squatters. Many sell fruits and food on street corners or take jobs as construction or domestic workers. Youth have few opportunities here and are at great risk of being recruited by armed groups. Often, refusal to join a group results in expulsion from Cazuca, or murder. The human rights NGO Justicia y Vida estimated there were more than 600 selective murders of teens between 2001 and 2006. Though numbers are believed to have dropped significantly in the past few years, youth continue to live with the threat of gangs and other armed actors who often enforce social codes of conduct and "cleanse" Cazuca of teens considered a blight on the barrios.

Though police presence has increased in recent years, residents say armed groups continue to control the barrios and intimidate the population. The office of the Human Rights Ombudsman of Soacha, the municipality that includes Cazuca, received complaints of 126 threats made against citizens in 2008, and it’s believed that many never announce threats made against them for fear of reprisal.

Amid the hardships, people have found innovative and resourceful ways to survive. They often reconstruct their lives with next to nothing, improvise homes and often subsist on little more than a dollar a day.