The impact of automatic deletion delay of DNA profiles of convicted offenders
DNA traces have made a significant contribution to criminal investigations for over 30 years, especially after the creation of DNA databases. Although the effectiveness of these databases is widely recognized, some issues – such as the retention period for DNA profiles – are still widely discussed because of the potential threat they pose to people’s fundamental rights and freedoms. In Switzerland, the length DNA is retained is determined through legal proceedings, which makes any decision to delete more complicated. Defining a time after which deletion would be automatic would simplify the removal procedure while both recognizing the usefulness of DNA in investigations and guaranteeing that it will not be retained indefinitely. This study looks at whether it is possible to delete a DNA profile from the database without affecting future investigations and proposes the most suitable delay before automatic deletion. Following the results of the study of Girardet (2014), delays of 5, 8, and 10 years were considered. Our sample, based on data in Switzerland’s national DNA database collected between 2005 and 2014 in four Swiss cantons, consisted of information on DNA samples from arrestees (N = 106 346) as well as identified biological traces (N = 16 516). Results show that removal of DNA profiles does not affect identification of the traces. In fact, 80 % of identifications occur in the year following the entry of an arrestee’s DNA profile, while the 20 % remaining are identified in a maximum of 10 years. In cases where identification of the traces required longer than 5 years (N = 313) or 8 years (N = 36), the offenses were almost all property crimes, although a few violent crimes were also observed. Based on the data available, automatic deletion after 10 years would ensure the efficiency of DNA database while respecting the proportionality of measure.