Towards Onsite Age Estimation of Semen Stains
Publication - July 2023
The age estimation of biological traces is one of the holy grails in forensic investigations. We developed a method for the age estimation of semen stains using fluorescence spectroscopy in conjunction with a stoichiometric ageing model. This is a first step towards onsite age estimation of semen stains using fluorescence spectroscopy.
Development of a Portable Fluorimeter
The model describes the degradation and generation rate of proteins and fluorescent oxidation products (FOX) over time. The previously used fluorimeter is a large benchtop device and requires system optimization for forensic applications. In situ applications have the advantage that measurements can be performed directly at the crime scene, without additional sampling or storage steps.
Therefore, a portable fiber-based fluorimeter was developed, consisting of two optimized light-emitting diodes (LEDs) and two spectrometers to allow the fluorescence protein and FOX measurements. The handheld fiber can be used without touching the traces, avoiding the destruction or contamination of the trace.
Successful Age Estimation Up To 11 Days
In this study, we have measured the ageing kinetics of semen stains over time using both our portable fluorimeter and a laboratory benchtop fluorimeter and compared their accuracies for the age estimation of semen stains. Successful age estimation was possible up to 11 days, with a mean absolute error of 1.0 days and 0.9 days for the portable and the benchtop fluorimeters, respectively. These results demonstrate the potential of using the portable fluorimeter for in situ applications.
Authors
- Nihad Achetib
- Caren Leemberg
- Mathijs Geurts
- Paul Bloemen
- Richard van den Elzen
- Maurice Aalders
- Annemieke van Dam
Forensic Science research group
From DNA testing to chemical analysis: modern techniques enable examination, in minute detail, of crime-scene materials. However, success and fairness depend on correct interpretation and evaluation. The Forensic Science research group is making an important contribution via its work with the police and other parties in the criminal justice chain.