Validation of SmartRank: A likelihood ratio software for searching national DNA databases with complex DNA profiles

Corina C G Benschop; Linda van de Merwe; Jeroen de Jong; Vanessa Vanvooren; Morgane Kempenaers; C P Kees van der Beek; Filippo Barni; Eusebio López Reyes; Léa Moulin; Laurent Pene; Hinda Haned; Titia Sijen

doi:10.1016/j.fsigen.2017.04.008

Validation of SmartRank: A likelihood ratio software for searching national DNA databases with complex DNA profiles

Forensic Sci Int Genet. 2017 Jul:29:145-153. doi: 10.1016/j.fsigen.2017.04.008. Epub 2017 Apr 15.

Authors

Affiliations

¹ Division of Biological Traces, Netherlands Forensic Institute, P.O. Box 24044, 2490AA, The Hague, The Netherlands. Electronic address: c.benschop@nfi.minvenj.nl.
² Division of Biological Traces, Netherlands Forensic Institute, P.O. Box 24044, 2490AA, The Hague, The Netherlands.
³ Forensic Software Engineering Unit, Digital and Biometric Traces Division, Netherlands Forensic Institute, P.O. Box 24044, 2490AA, The Hague, The Netherlands.
⁴ DNA Database Unit, National Institute of Criminalistics and Criminology, Brussels, Belgium.
⁵ DNA database department, Netherlands Forensic Institute, P.O. Box 24044, 2490AA, The Hague, The Netherlands.
⁶ Forensic Biology Unit, Scientific Investigations Department (RIS) of Rome, Carabinieri Scientific Investigations Group (RaCIS), Viale di Tor di Quinto 119, 00191, Rome, Italy.
⁷ Scientific Commissary General of Police, National Police, Madrid, Spain.
⁸ National Forensic Science Institute, Ecully, France.
⁹ Ahold Delhaize, HR Analytics, Provincialeweg 11, 1506 MA, Zaandam, The Netherlands.

PMID: 28441635
DOI: 10.1016/j.fsigen.2017.04.008

Abstract

Searching a national DNA database with complex and incomplete profiles usually yields very large numbers of possible matches that can present many candidate suspects to be further investigated by the forensic scientist and/or police. Current practice in most forensic laboratories consists of ordering these 'hits' based on the number of matching alleles with the searched profile. Thus, candidate profiles that share the same number of matching alleles are not differentiated and due to the lack of other ranking criteria for the candidate list it may be difficult to discern a true match from the false positives or notice that all candidates are in fact false positives. SmartRank was developed to put forward only relevant candidates and rank them accordingly. The SmartRank software computes a likelihood ratio (LR) for the searched profile and each profile in the DNA database and ranks database entries above a defined LR threshold according to the calculated LR. In this study, we examined for mixed DNA profiles of variable complexity whether the true donors are retrieved, what the number of false positives above an LR threshold is and the ranking position of the true donors. Using 343 mixed DNA profiles over 750 SmartRank searches were performed. In addition, the performance of SmartRank and CODIS were compared regarding DNA database searches and SmartRank was found complementary to CODIS. We also describe the applicable domain of SmartRank and provide guidelines. The SmartRank software is open-source and freely available. Using the best practice guidelines, SmartRank enables obtaining investigative leads in criminal cases lacking a suspect.

Keywords: CODIS; DNA database; Forensic science; LRmix; Likelihood ratio; SmartRank.

Publication types

Validation Study

MeSH terms

DNA Fingerprinting*
Databases, Nucleic Acid*
Forensic Genetics
Humans
Likelihood Functions*
Software*