Pioneered by SFI, Particle Combination Analysis (PCA) is the use of co-occurring particles to independently and quantitatively test alternative attribution hypotheses.
The concept and potential of PCA have been known for a long time.
Over the last few years Stoney Forensic has done three things to move this capability from a theoretical concept to a proven capability:
- We have been able to demonstrate the feasibility of applying the concept to practical problems, and
- We have developed practical methods to enable Program Managers to incorporate PCA on a routine, cost effective basis.
- We have developed quantitative methods allowing objective measurements of the degree of association resulting from comparisons of particle profiles.
SAME - DIFFERENT
Very Small Particles are everywhere - dusts, pollen, scents, vapors, molecules. There are literally thousands of particles on everyone and everything. They come from far away, from people who are nearby, and from each location passed through. They adhere to clothes and objects resulting in a mix of particles with almost infinite variation, creating a particle signature that has the potential to convey where something was made, where it has been, who has been around it, whether it has been near another specific person, object, activity, etc.
Over the past 20 years, in support of government and commercial investigations, we have developed a capability that integrates a range of specialized microscopic, chemical and instrumental techniques to isolate and analyze extremely small quantities of these dusts and integrate these results to produce extraordinarily accurate and reliable information about where a person or object has been, what activities were going on nearby and whether they can be linked to other specific objects, people or places.
We have applied this capability to dusts from people, clothing, computer components, commercial drugs, contraband drugs, manufactured goods, packaging materials, weapons, explosive devices, recovered property and vehicles. There have been notable successes in determining country of origin, location of manufacturing site, distribution networks, activities taking place at inaccessible locations, and links between people, locations activities and objects.Our approach differs from other methods and approaches in the number of different kinds of particles that are analyzed, what properties are measured, and how the results are used and interpreted.