His research interests include socio-territorial boundaries and mobility, violence and inequality, and political ecology. Among his books are A Not-so-distant Horror: Mass Violence in East Timor (Cornell University Press, 2005); Dying to Live: A Story of U.S. Immigration in an Age of Global Apartheid (City Lights Books, 2008), and Operation Gatekeeper and Beyond: The War on “Illegals” and the Remaking of the U.S.-Mexico Boundary (Routledge, 2010).