1. Science of Crime Scenes
Chapter 3.0
Science of Crime Scenes

2. Science of Crime Scenes
Personnel
CSI typically must have a minimum of a four-year degree in science
Many have advanced degrees and even internships with forensic agencies
A new employee will need time, experience, and training
The training will be a mixture of in-house and external training
The training has to be continuous, as the field of forensic science changes constantly
Science of Crime Scenes

3. Post-Traumatic Stress Disorder (PTSD) for CSIs
The physical and psychological problems that may be experienced by first-responders, such as police officers have also been well documented
Police, firefighters, and medical personnel
No specific research regarding CSIs' stress levels after processing traumatic death events exists
Not considered in the first responder category
May be overlooked because they respond from the laboratory
Science of Crime Scenes

4. Physical responses to trauma
Stomach upset and trouble eating
Trouble sleeping and feeling very tired
Pounding heart
Rapid breathing
Feeling edgy, sweating, severe headache if thinking of the event
Failure to engage in exercise, diet, safe sex, regular health care
Excess smoking, alcohol, drugs, and food
Science of Crime Scenes

5. Emotional responses to trauma
Feeling nervous, helpless, fearful, or sad,
Feeling shocked, numb, and not able to feel love or joy
Avoiding people, places, and things related to the event
Being irritable or having outbursts of anger
Becoming easily upset or agitated
Blaming yourself or having negative views of oneself or the world
Distrust of others
Getting into conflicts, being over-controlling, being withdrawn
Feeling rejected, or abandoned, loss of intimacy or feeling detached
Science of Crime Scenes

6. Science of Crime Scenes
What help is available
An agency psychologist
Critical incident stress debriefing (CISD)
Employee assistance program (EAP)
If after treatment the CSI decides to leave the team, this should not reflect on his reputation in a negative way
Long-term crime scene investigation is not for everyone
Science of Crime Scenes

7. Science of Crime Scenes
Contamination
Only a few cells are needed to detect a useful DNA profile
Therefore, only a few cells are needed to contaminate a DNA sample
The principal sources of DNA contamination are:
from personnel to the exhibit/DNA sample
from contaminated consumables (for example, swabs, tubes, personal protective equipment (PPE)/ barrier clothing) to the exhibit/DNA sample
from exhibit to exhibit or DNA sample to DNA sample
from contaminated equipment not properly cleaned from previous scenes (for example, cameras, tripods, step plates).
Science of Crime Scenes

8. How contamination occurs
Directly
For example, saliva or dandruff from an examiner ending up on an exhibit
Indirectly
For example, biological material present on a drawer handle is transferred on to the gloves of an examiner who opens the drawer, fails to change their outer pair of gloves and then handles a significant item, resulting in the indirect transfer of biological material from the handle of the drawer to the item)
Science of Crime Scenes

9. How to avoid contamination
Limit attendance at crime scenes to absolutely only the essential responders
Make sure everyone wears protective clothing that is also designed to limit transfer of evidence, such as booties, head covers, vinyl gloves
Use disposable evidence collection tools such as plastic forceps
Use disposable pens and writing materials
Thoroughly clean cameras and other documentation equipment between crime scenes
Science of Crime Scenes

10. Use off-site facilities
No matter how urgent, do not satisfy your biological needs at the crime scene.
Whenever you need to eat, drink, or go to the bathroom, and even if you must smoke use off-site facilities.
Science of Crime Scenes

11. The Iron Triangle of Success
Cost
Time
Quality
CSIs have limited resources and must work optimally with what is available
Science of Crime Scenes

12. Science of Crime Scenes
Team vs. Ego
Team: two or more people who are working together.
Ego: your sense of your own value and importance; the part of the mind that is responsible for your sense of who you are.
Individuals need to sufficiently suppress their egos to the team’s ultimate goal of a successful crime scene
Each team member contributes to the success of investigation
Each has a specific role and may not be employed by the investigating agency, but you must work with the other team members to accomplish the overall objectives
Individuals must never lose sight of the bigger picture
Science of Crime Scenes