He is the author of Illegality, Inc.: Clandestine migration and the business of bordering Europe (University of California Press 2014), which won the 2015 BBC/British Sociological Association Ethnography Award. He has written extensively on border security, irregular migration and related topics, with specific reference to West Africa and southern Europe. His ongoing research is concerned with security risk and the ‘mapping of danger’ in international crisis interventions from a comparative perspective, building on his fieldwork in Mali.