Hans Nelen is a criminologist and has a law degree. Between 1986 and the beginning of 2001 he was employed as a senior researcher and research supervisor at the Research and Documentation Centre of the Ministry of Justice in the Netherlands (WODC),  mainly involved in drug, fraud, organised crime, corporate crime and police research. Between 2001 and 2006 he was a senior lecturer and senior researcher at the Institute of Criminology of the Vrije Universiteit in Amsterdam. Since January 1, 2007 Nelen has been working as a professor of criminology at the UM.