1. Science of Crime Scenes
Chapter 4.1
Science of Crime Scenes

2. Science of Crime Scenes
Preliminary Search
Visually identifying the presence of obvious physical evidence will direct the method of searching for less visible evidence
Points of entry and exit should always be checked for signs of fingerprints, shoeprints, and toolmarks from forced entry
There should be a search for any evidence that helps to establish how many people were present
Look for signs of items or objects that look out of place
Look for signs of struggle, like knocked over furniture, broken fixtures and lamps, broken glassware and bottles, or broken windows
Science of Crime Scenes

3. Science of Crime Scenes
Recognizing Evidence
Physical evidence can be anything
Unseen DNA from a few cells
Buildings and cities (like in 9/11)
CSI needs a thorough grounding in all the forensic disciplines
It is always better to admit ignorance, but know who to call to find out the answer
Expect the unexpected
Science of Crime Scenes

4. Science of Crime Scenes
A bullet’s trajectory was difficult to interpret until a portion of the electrical socket cover was removed—expect the unexpected and don’t fall prey to your assumptions
Science of Crime Scenes

5. “My phone contact list.”
Dr. Amy Mundorff, a forensic anthropologist who was in charge of the anthropological examinations of the victims of the September 11, 2001 attacks on New York, was once asked what was the one thing she had now that she wished she’d had when working on that case
Science of Crime Scenes

6. Science of Crime Scenes
Recovering Evidence
There are several different methods of systematically searching for evidence
Strip or lane search method
Grid or checkerboard method
Spiral method
Trail method
Which of these is employed principally depends on the type of crime scene you have, and the personnel available.
Science of Crime Scenes

7. Science of Crime Scenes

8. Science of Crime Scenes
Recording Evidence
Because of court, note-taking is the most important task for the investigator at a crime scene
Notes must be:
Chronological and continuous
Detailed and specific
Complete
Legible and permanent
Science of Crime Scenes

9. Chronological and continuous
The notes begin before entering the scene
The opening notes will contain details such as
which investigators are present at the scene
the scene location
the time and date the investigator was contacted
the time the investigator arrived at the scene
the names and contact information of the detectives who contacted the investigator
a brief synopsis of the information given to the investigator before he enters the scene
Science of Crime Scenes

10. Science of Crime Scenes
Detailed and specific
Descriptions such as “There was blood on the light switch” provide little information
Better:
“The white plastic light plate inside the front door has two bloodlike smears. These smears tested presumptively positive for blood with phenolphthalin. The smears are on the upper edge of the plate, 47½ inches from the floor and 16 inches from the north end of the east wall. A sample of the bloodlike smear on the north side of the plate was collected as item TMCA-6.”
Science of Crime Scenes

11. Science of Crime Scenes
Complete
The notes must describe every observation, every action, every result of testing, and the collection of every item of physical evidence that occurs
Every result, positive or negative, must be noted
Before the investigator leaves, the disposition of every evidence item must be noted, with descriptions of the packaging and seals applied to each
Science of Crime Scenes

12. Science of Crime Scenes
Legible and permanent
The notes must be written in such a way that they can be easily read by anyone
They must be written in permanent ink so that changes are not easily made
Any errors to the notes that are noticed should be crossed out using a single strike-through, and the author’s initials and date noted beside the strike- through
The more organized and easily read the scene notes are, the less likely there will be any misunderstandings about meaning or content
Science of Crime Scenes

13. Science of Crime Scenes
Death Investigations
It is important that the crime scene investigation team know the preliminary manner in which the victim died as soon as possible
There are only five manners of death: natural, accidental, homicide, suicide, undetermined
The cause of death is the disease or injury responsible for the lethal sequence of events.
Without moving or touching the body in any way, the investigators can do a visual inspection for the presence of any wounds
Science of Crime Scenes

14. Science of Crime Scenes
Gunshot wounds
Gunshot wounds can provide useful information
Entrance wounds where a bullet entered the body are usually, but not always, smaller than the exit wound
They may be clean and well defined and there may be blackening around the edges
Often little blood is associated with this wound
The presence of tattooing or stippling that occurs when gunpowder is deposited beneath the skin can help to determine that the muzzle of the weapon was in close proximity to the skin when the gun was discharged
Exit wounds are larger and more irregular in shape, with more associated blood
Science of Crime Scenes

15. Science of Crime Scenes
Defensive wounds
Wounds caused during a struggle between a victim and the attacker
Slashing wounds to the fingers, forearms, or puncture wounds to the rest of the hands as a result of trying to ward off numerous knife stabbing attempts
In cases where a victim defends himself from a beating, there may be defense wounds in the form of abrasions or bruises on the forearms
Science of Crime Scenes