Abstract
It has been advocated before that appearance prediction of unknown suspects from crime scene DNA, in the
context of Forensic DNA Phenotyping (FDP), is mostly suitable for single source DNA samples, whereas FDP from
DNA mixtures to which more than one person contributed, is viewed challenging. With this report on a murder
case, we practically demonstrate the feasibility of appearance DNA prediction of an unknown suspect from a
mixed crime scene trace, to which the unknown suspect and the known victim had contributed. From this twoperson DNA mixture, we successfully predicted eye, hair and skin color of the unknown suspect with the
HIrisPlex-S system by applying targeted massively parallel sequencing (MPS). We argue that at least three factors
benefit appearance DNA prediction of unknown suspects from mixed crime scene traces, which were met in this
murder case: i) SNP genotype knowledge from reference DNA analysis for one of the two persons in the mixture
(here the known victim), ii) about equal DNA contributions by both donors to the mixed crime scene stain, and
iii) the use of MPS allowing quantitative SNP analysis. Moreover, we show that additionally analyzing animal
DNA in this mixed crime scene trace provides further investigative information. We envision that the investigative DNA strategy that we applied here for analyzing a two-person mixed crime scene trace in a murder case,
will be applied in the future to more criminal cases with two-person DNA mixtures, for instance sexual assault
cases.
context of Forensic DNA Phenotyping (FDP), is mostly suitable for single source DNA samples, whereas FDP from
DNA mixtures to which more than one person contributed, is viewed challenging. With this report on a murder
case, we practically demonstrate the feasibility of appearance DNA prediction of an unknown suspect from a
mixed crime scene trace, to which the unknown suspect and the known victim had contributed. From this twoperson DNA mixture, we successfully predicted eye, hair and skin color of the unknown suspect with the
HIrisPlex-S system by applying targeted massively parallel sequencing (MPS). We argue that at least three factors
benefit appearance DNA prediction of unknown suspects from mixed crime scene traces, which were met in this
murder case: i) SNP genotype knowledge from reference DNA analysis for one of the two persons in the mixture
(here the known victim), ii) about equal DNA contributions by both donors to the mixed crime scene stain, and
iii) the use of MPS allowing quantitative SNP analysis. Moreover, we show that additionally analyzing animal
DNA in this mixed crime scene trace provides further investigative information. We envision that the investigative DNA strategy that we applied here for analyzing a two-person mixed crime scene trace in a murder case,
will be applied in the future to more criminal cases with two-person DNA mixtures, for instance sexual assault
cases.
| Original language | English |
|---|---|
| Article number | 102557 |
| Number of pages | 8 |
| Journal | Forensic Science International: Genetics |
| Volume | 54 |
| DOIs | |
| Publication status | Published - 20 Jun 2021 |
Bibliographical note
AcknowledgementsThis work was financed in part by the law enforcement client, for
whom this forensic service DNA testing was performed. The authors are
supported by Erasmus MC, University Medical Center Rotterdam.
