New Open Source Software for Bloodstains

A paper recently released by Daniel Attinger, Ph.D. describes "fundamental and collaborative research to better understand the formation of bloodstains."



From the abstract of Development of a Science Base and Open Source Software for Bloodstain Pattern Analysis:

Bloodstains are signs of a violent crime and help determine how the crime happened. However, Bloodstain Pattern Analysis is not straightforward because of the physical relation between blood impact and the resulting bloodstains is non-linear.

This report describes fundamental and collaborative research to better understand the formation of bloodstains.

The methods of strings and of the tangent typically used in today’s crime scenes are first-order approach to reconstruct trajectories. They assume that the droplets travel in straight lines, but by neglecting drag and gravity forces, these approaches induce systematic and poorly quantified uncertainties.

The major goals of this project were to:

1) Perform a fundamental and collaborative research to better understand the formation of bloodstains;

2) Deliver a knowledge base, innovative measurement methods, and pieces of open-source analysis software to help bloodstain pattern analysts better answer the following question: How was this violent crime committed?

The primary results of this project are a better characterization of the viscosity and surface tension of blood, a novel method to determine the region of origin of a blood spatter, and the fostering of connections between the fluid dynamics community and the bloodstain pattern analysis community.

Through this research, a method to reconstruct the curved trajectories of blood drops from 3D inspection of blood spatters has been developed. The method works in a laboratory setting, and on very flat substrates. This method is based on sound fluid mechanics principles and is about four times more accurate than the current methods based on straight trajectories.

But it is unlikely that the method will be used widely in the near future since 3D microscopes retail for $50,000 and any surface rougher than 1 micrometer will likely create too much noise in the measurement of stain volumes.

Researchers acknowledge that there is a need for more research on the physical properties of blood, and their variation among individuals. Additionally, the complexity of the physical properties of blood makes it unlikely that satisfactory synthetic substitutes of blood will be found in the near future.

You can download a full PDF of the report here.

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