Research article
Comparing the growth and effectiveness of forensic DNA databases

https://doi.org/10.1016/j.fsigss.2007.11.011Get rights and content

Abstract

Forensic DNA databases have altered the landscape of the criminal justice system and re-shaped the field of forensic science. Whilst there has been widespread commentary regarding the legal and socio-political basis of DNA databases, there remains a lack of meaningful empirical assessment of database performance and effectiveness. In this research DNA database growth and effectiveness has been assessed statistically from data collated from major international databases.

Introduction

Forensic DNA databases have altered the landscape of the criminal justice system and re-shaped the field of forensic science. They have provided new challenges to the mechanisms by which forensic evidence can be utilised and increased the onus of responsibility on those who administer their use. The growth of DNA databases internationally has been rapid with millions of STR profiles now held from convicted offenders, suspects and unsolved crimes. Links provided through DNA database searches have contributed valuable intelligence to hundreds of thousands of police investigations, often for crimes that are notoriously difficult to resolve. There has been widespread commentary regarding the legal and socio-political basis of DNA databases, but there remains a lack of meaningful empirical assessment of database performance and effectiveness. In this research DNA database growth and effectiveness has been assessed statistically from data collated from major international databases.

Section snippets

Modelling the growth of DNA databases

We began by modelling the publicly available data from four major global databases (USA – CODIS, UK NDNAD, Europe – ENFSI, and Canada) to assess trends in the rate of DNA Database growth (Fig. 1, Fig. 2). In some cases the data available was available at monthly intervals, whereas for others it was collated six-monthly or annually. It was not possible to assess growth characteristics for the European (ENFSI) data available. Initially a linear model was fitted to each dataset using Microsoft

Modelling effectiveness of DNA databases

A limitation of any assessment of effectiveness is that only crude measures of return are available. Typically DNA database administrators rely on a hit rate (HR) to describe effectiveness. This is calculated as the number of hits obtained per profile loaded. For this study we have utilised this measure also. In addition we have calculated a “return index” (RI) from available data, by RI = NH/NS, where NH is total hits obtained for total samples analysed NS. For the databases under study, these

Summary

Varying trends are obvious when the growth rate of major DNA databases is compared. In the next phase of analysis we will map these changes against significant external impacts such as public policy or legislative shifts. A crude assessment of return can inform administrators as to the drivers of positive outcomes from DNA databases. Whilst further analysis and research is required in this area this study provides a basis for more detailed modelling.

Acknowledgements

Our thanks go to the various DNA database administrators who have collaborated with us in our work, which is only partially represented here. SJW also acknowledges the financial assistance of Faculty of Science, UTS who have supported this project and attendance at the 22nd ISFG Congress, 2007.

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