This study proposes a methodology for estimating the hidden criminal population working in markets of drug
trafficking, prostitution exploitation and smuggling in Italy during the period 2006–2014. These estimates
represent the first step of a wide procedure that has the final objective of measuring the economic flows of illegal
transactions in national accounts. We exploit administrative registers coming from the Ministry of Justice, and
consider these registers as lists of potential criminals. Unique codes for denounced criminals are not available,
limiting so far its exploitation at micro level. This drawback has been overcome in this work by proposing an
adjustment of the Zelterman estimator that accounts for the potential linkage errors caused by the lack of exact
unique identifiers in the dataset. We obtain yearly estimates of the population size of criminals including also
the unknown population, for the crimes of drug trafficking, prostitution exploitation and smuggling during
the period 2006–2014
