5thEuropeanIABPAconferenceFinal programm

The 5 th European
Internaonal Associaon
of Bloodstain Paern Analysts
(IABPA) Conference
Rome 2015
Impact velocity of blood droplets for crime
scene reconstruction
Nick Laan ‐ University of Amsterdam
Abstract
Within Bloodstain Pattern Analysis, forensic
experts commonly use the stringing
method, based on a straight line
approximation of the blood droplet trajectories
to determine where the source
of a bloodstain pattern was. However,
by ignoring gravity, errors as large as
45 cm may arise when inferring the 3Dlocation
of the wound. Accordingly, it is
impossible to discern, e.g., between a
standing or sitting position of the victim.
To reconstruct the trajectories correctly,
the impact velocity of the droplets
needs to be determined. We show
how this can be done directly from the
shape and volume of dried bloodstains.
By using advanced fluid dynamics based
on a balance of inertial, viscous and
capillary forces, we are able to determine
the impact velocity of the bloodstains.
In this way, we are able to determine
the curved trajectory by taking
gravity into account. With a proof-ofprinciple
experiment we show that our
method reduces the uncertainty in the
reconstructed height of the origin of the
bloodstains significantly, making it possible
to determine the position of, e.g.,
a victim much more accurately.
Biography
In 2008 Nick Laan obtained his Bachelor of
Science in Physics at the Vrije Universiteit (VU)
in Amsterdam. Nick obtained his Master of Science
at the University of Amsterdam in 2011.
During his Masters he did a project on the Academic
Medical Centre (AMC) of Amsterdam
under supervision of Dr. M.C.G. Aalders and Dr.
R.H. Bremmer of which the work has been published.
His Master thesis was a collaborative
project with the AMC and the Netherlands Forensic
Institute (NFI). In this project, the use of
Optical Coherence Tomography in volume determination
of a blood drop was investigated.
The project was done under supervision of Dr.
M.C.G. Aalders and Dr. K.G. de Bruin.
After finishing his Master, Nick started his PhD
at the University of Amsterdam under the supervision
of Dr. K.G. de Bruin and Prof. Dr. D.
Bonn. As part of the Soft Matter group from the
Institute of Physics (IoP), Nick incorporates
fluid dynamics with Bloodstain Pattern Analysis
(BPA). The subject of his PhD is to investigate
whether the velocity of a blood drop can be
determined from a dried bloodstain to improve
BPA methodologies which are used on crimes
scenes. In 2012, Nick received the Best Poster
Award at the European Academy of Forensic
Science, for his novel work in combining fluid
dynamics with BPA.
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