1. Forensic Science
Unit D: Summary

2. Forensic Engineering Concerned with:
Failure analysis
Accident reconstruction
Cause and origin of fires or explosions
Answer questions such as how did an accident occur or what structural failure occurred

3. Forensic Pathology
Involves the investigation of sudden, unnatural, unexplained, or violent deaths.
Typically these are the medical examiners or coroners
Answer questions: who is the victim, what injuries are present, when did the injuries occur, why and how were the injuries produced, and what is the cause of death

4. Criminalist (CSI)
Analyzes, compares, identifies, & interprets physical evidence at crime scenes.
Criminalists examine and identify physical evidence to reconstruct a crime scene. Physical evidence can be a weapon, a piece of clothing, a bloodstain, drugs, or even a vapor in the air. Criminalists use physical evidence to provide a connection between the suspect and the victim. Such connections are acquired by the transfer of hair or clothing fibers from a suspect to the victim. Other connecting links are fingerprints, bullets, or shoe impressions. Physical evidence is collected from a crime scene that includes the victim's body and the surrounding area of the crime.

5. Forensic Anthropology
Identification and examination of human skeletal remains
Trying to determine origin, sex, approximate age, race and skeletal injury
May create facial reconstruction
Identify victims of mass disaster such as plane crash

6. Forensic Toxicologist
Analyses alcohol, drugs, & poisons in body fluids for the benefit of the courts.
Forensic toxicology is essentially a specialty area of analytical chemistry which specifically looks at body fluids for presence of drugs, poisons, and/or alcohol.

7. Manner of Death
Natural:
Homicide
Suicide
Accidental
Undetermined

8. Cause of Death Asphyxiation Exsanguination Blunt force trauma
Strangulation
Drowning
Fire victim
Exsanguination
Major blood loss
Blunt force trauma
Sharp force trauma
Chemical trauma

9. Estimated Time of Death
Autopsy
Rigor Mortis: the stiffening of body parts in the position they are in when death occurs.
Lividity: medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground
Body Temp: postmortem changes that cause a body to lose heat o C/hr

10. Estimated Time of Death
Livor Mortis or lividity: medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground. Begins immediately after death and lasts for 12 hours
Algor Mortis: postmortem changes that cause a body to lose heat. Process in which the body continues to cool to room temperature. 1 – 1.5 degree/hour

11. Forensic Entomology
Study of insects and their relation to a criminal investigation
After decomposition begins, insects such as blow flies are the first to infest the body

12. Arriving at the Crime Scene
Secure and isolate the crime scene
Determine boundaries of crime scene and priorities for evidence collection
Rough sketch
Finished sketch
Photograph
Videotaping
Notes

13. Collecting Evidence
Conduct a systematic search for evidence; be unabiased and thorough.
Field technicians
What to look for depends on the crime and what specific locations of the crime scene would most likely be affected
Microscopic or massive objects
Collect carriers of possible evidence
Vacuum or sweeping collected

14. Packaging of Evidence
Prevent any changes from occurring (contamination, breakage, evaporation, bending, loss)
Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possible
Package evidence separately

15. Chain of custody
Continuity of possession; every person who touched it must be accounted for
Standards for collecting, labeling, and submitting evidence forms are necessary for court
Labels include collectors initials, location of evidence, date of collection. Identification numbers must also be used

16. Submission of Evidence
Standard/reference samples
Substance controls
Evidence submission form will detail the evidence collect and particular type of examination/analysis requested.
Lab tech not bound by requests

17. Methods of Detection Types of prints
Latent print
Visible print – deposited ink, blood, dirt
Plastic print – impression in a soft surface
Most natural finger prints consists of secretions of the skin’s glands
Developed by either powders or chemicals

18. Fingerprints History 3 Patterns
Japanese used thumb print as a signature on documents until 1860.
First used in crime in 1901 by Sir Edward Richard Henry
3 Patterns
Whorl
Loop
Arch

19. Categories of Fingerprints
Loop – ridge lines enter one side of pattern and curve around to exit from the same side of pattern. (65%)
Whorl – ridge lines rounded or circular and have two deltas(30-35%)
Arch – ridge lines enter print from one side and exit from the other (5%)

20. Blood Evidence
Serology: the study of antigen – antibody reactions using laboratory tests
Kastle-Myer Test – Is it blood?
Precipitin Test – Is it human blood?
DNA Analysis – Whose blood is it?

21. ABO blood typing
RBCs have A, B, neither, or both antigens in its surface. Serum carries antibodies against antigens it does not have. O negative carries no Ag and therefore does not react with any Anti A, B, AB. Rh factor is a separate protein on the surface of RBCs
Pos reaction
Neg reaction

22. Blood Splatter Analysis
Location, distribution, and appearance of blood stains are an important part of forensics
Investigators try to determine:
Direction
Dropping distance
Angle of impact
Splatter analysis is often used for crime scene reconstruction

23. Blood Splatter Analysis
Factors which influence stain patterns are:
Surface texture
Direction of travel
Pointed end of bloodstain always faces its direction of travel
Angle of impact is determined by measuring the degree of circular distortion of the stain
Blood striking a surface at right angles gives rise to a nearly circular stain
As the angle decreases, the stain becomes elongated in shape