Between 1985 and 1990 he did comparative observational research on the behaviour of people during critical public order incidents (football riots, political demonstrations, etc.) in the Netherlands. For this field research he recorded interactions between hooligans, violent demonstrators and the police during over 250 riots and riot-situations. Some of the international publicity following this research focused on the supposed parallels with the earlier chimpanzee study. In 1998 "Hooligans, autonomen, agenten" appeared, the book on the riot observations.
From 1991 to 1998 he was researcher and consultant at the PIOV Research Centre Public order and Safety (Hoogerheide, the Netherlands), where he co-ordinated research on public order policing, use of force, pepper spray, bomb-threats and crisis management. Between 1998 and 2004 he was research manager at the LSOP Police Knowledge and Education Centre (Apeldoorn, the Netherlands), where he initiated a research programme "Managing Dangerous Situations", which focuses on interactions between the police and the public in potentially violent or dangerous situations. Presently, Otto is Chair, Public Order Management at the Police Academy of the Netherlands in Apeldoorn, and professor Security and Collective Behaviour at the University of Groningen