1. Science of Crime Scenes
Introduction
Science of Crime Scenes

2. The past is a mystery of necessity
Humans love mysteries and discovery, whether it is about people, places, or things
Past events cannot be experienced in the present, the past must be interpreted through:
Documents
Living participants
Objects
Some are intentional, others unintentional
Science of Crime Scenes

3. Forensic science is a historical science
A crime scene investigator (a CSI) or forensic scientist infers past criminal activity through the traces left by those involved (criminal and otherwise)
Much like historians, archeologists, geologists, paleontologists, and others
Science of Crime Scenes

4. Science of Crime Scenes
Popular but with flaws
Forensic science has always been popular but television and movies have made it much more so
The popular focus on forensic science was quickly followed by interest in some of its problems
Unethical employees
Errors
Wrongful convictions
The patchwork jurisdictional nature of law and law enforcement, particularly in the United States, fragmented methods, approaches, and training
Science of Crime Scenes

5. National Research Council Report, 2009
“Although research has been done in some disciplines, there is a notable dearth of peer-reviewed, published studies establishing the scientific bases and validity of many forensic methods”
Science of Crime Scenes

6. What are the problems in forensic science?
The complexity of nature and modern material culture
The discipline’s focus on the individual
The perception that forensic science is “only an applied science”
The confounding effects of taphonomic processes
Science of Crime Scenes

7. Problem 1: The complexity of nature and modern material culture
Material culture refers to the physical aspects of a society, the objects made or modified by a human
These objects surround a people and its activities and are defined by their properties
When an object interacts with other objects or humans, it gains meaning and develops performance characteristics
Science of Crime Scenes

8. Science of Crime Scenes
Two Examples
A baseball thrown through the window of a house
A rock thrown through the window of a car
Science of Crime Scenes

9. What must be understood
In Event 1, the materials in play are quite different than in Event 2
Need to understand:
what the objects are
also the nature of their components
the way those components were combined by natural or human actions
the way they interacted.
The interaction involves all the physics of the action (velocity, angle, rotation, surfaces, etc.) and the interaction (the rock, the window coating, the baseball, the plate glass) to produce the final results.
Science of Crime Scenes

10. CSIs think in the abstract and the practical
“Could a rock really have broken that auto window?”
“Could this rock really have broken that auto window?”
Consider all the possible combinations of interactions that occur all day long across the world and add to that those that involve alleged criminal activities.
Not only do CSIs have to work with the world as it is but they also have to sort the criminal activity from everyday life
Science of Crime Scenes

11. Problem 2: The Tyranny of the Particular
Forensic science’s focus on individual, singular things creates additional complexities unknown to other sciences
Other historical sciences work at different scales of observation
Archaeology = social
Geology = global
Astronomy = universal
An archaeologist would analyze all porcelain ceramics or porcelains from the St. James’ factory
A forensic scientist would analyze this specific porcelain object as an object and its relation to a specific crime.
Science of Crime Scenes

12. Most sciences don’t work to the particular
Other sciences use deduction:
From the specific (observations in an experiment, for example)
to the general (development of principles or laws about phenomena in the world)
But forensic science tends to use induction:
From the general (all automotive paints, as an example)
to the specific (the paint on the automobile in the current case
Science of Crime Scenes

13. Avoid fallacies common to induction
The fallacies of illicit transference
The fallacy of composition: what is true of the parts is true of the whole
If a red cotton fiber is found, the textile it came from need not be made only of red cotton
The fallacy of division: what is true of the whole is true of it parts
DNA from a person’s hair must match DNA from their blood (chimerism is when a person’s DNA sequence varies with tissue sampled)
Science of Crime Scenes

14. Problem 3: A Book of Recipes
Basic research leads to knowledge about the world, applied research leads to solutions to specific questions
Forensic science is often classified as applied science because of its direct applicability to solving crime
This takes a narrow and simplistic view of forensic science
Forensic science studies a range of phenomena that no other science pays attention to in a way no other science does
Forensic and crime scene science still has an uphill battle to fight to gain recognition as a “real” science
Science of Crime Scenes

15. Problem 4: Entropy and Taphonomy
Entropy: Loss of organization
Taphonomy: Study of an organism from the time it dies
These processes are at the heart of forensic science
Few other sciences study them
Not much literature or interest
Science of Crime Scenes

16. Crime scenes are a process, not an event
More than “bagging and tagging”
If the crime scene is compromised, the entire case may be jeopardized
Those who process crime scenes are—or should be—scientists with the requisite education and training appropriate for that kind of work
Science of Crime Scenes

17. Systematic approach to crime scenes
Protecting the scene(s)
Documentation of the location, scene, and evidence
Collection of the potential evidence
Preservation of the evidence
Labeling of evidence and related materials
Chain-of-custody considerations
Letter of transmittal (to the custodial agency or laboratory)
Collection of reference materials (known samples for comparison)
Science of Crime Scenes