1. Biological Forensics

2. Forensics Lab Objectives
Learn the definition of forensic science.
Examine ways biological information can be used to solve crimes, and see examples of this in today’s society.

3. Forensic Science
Definition: The application of the tools of science, as well as specific scientific facts, to help solve legal problems
Goal: the determination of the cause, location, and time of death

4. Some Uses of Forensics
Identify potential suspects whose DNA may match evidence left at crime scenes
Exonerate persons wrongly accused of crimes
Identify crime and catastrophe victims
Establish timing and circumstances of a crime

5. Categories of Forensics
DNA Evidence
Forensic Entomology
Forensic Serology
Forensic Odontology
Forensic Entomology
Study of insects to estimate the time of death
Insects lay eggs that hatch into larvae
Stages of development tell how long ago the eggs were laid
Temperature and other weather conditions affect the development
Serology: looking at blood serum, also % of the population are secretors: saliva, semen, vaginal fluid
Historical methods of identifying and individualizing blood and other body fluids
Antigen-Antibody reactions
Enzyme-Substrate reactions
Odontology looks at dental records in order to identify victim, also bitemarks on victim or objects at crime scene
Bluebottle blow fly

6. Radiocarbon dating of the Dead Sea Scrolls
Forensic Fingerprinting
Fingerprint counting number of typica
Forensic Anthropology
Radiocarbon dating of the Dead Sea Scrolls
As each atom decays, it changes from carbon to nitrogen and in the process emits a particle called an electron – this is radioactivity. These radioactive emissions can be measured to find out how much radiocarbon has decayed and how much still remains. C14 has a half-life of 5,730 years, which means that the level of radioactivity will fall by half its original amount over that period. So from the proportion of C14 to C12 in the organism, scientists can work out reliably how long ago it died.
Forensic Antrhopology:
Identification and examination of skeletal remains
Bones can reveal species, sex, approximate age, race and skeletal injury
Facial reconstruction can help identify “John or Jane Doe”
Forensic Art
Composite art, image modification, age progression, post-mortem reconstruction and demonstrative evidence

7. Bloodstain Pattern Analysis Forensic Photography
Forensic Pathology
Forensic Psychiatry
Forensic Toxicology
Bloodstain Pattern Analysis
Forensic Photography
Forensic Pathology
Investigation of sudden, unnatural, unexplained or violent deaths
Autopsy performed to establish the cause of death
Manner of death classified as natural, homicide, suicide, accident or undetermined
Time of death determined by rigor mortis, livor mortis and algor mortis
Forensic pathology: coroner, 50% of deaths observed are by natural causes
Forensic Psychiatry
Study of human behavior
Determine if persons are competent to stand trial
Develop a suspect’s behavioral profile based on previous patterns of other criminals Psychology: often testifies in a court, for example, if they feel a person may be competent to stand on trial,
Toxocology: tests different toxins in body, ie. Death due to poisoning, or perhaps accidental death due to bee sting
Bloodstain pattern analysis gives an idea of what actually occurred at time of death, experts are careful of bugs and cockroaches that spread blood around

8. Biological Forensics Use of Entomology Use of Molecular biology
(the study of insects)
Use of Molecular biology
(DNA analysis)

9. Molecular Forensics
Use of identifying characteristics of molecules in our cells to aid legal investigations
Compare the DNA and/or blood type of crime scene evidence to that of suspects, or use this information to identify a victim.

10. Two main methods of Molecular Forensics
PCR (Polymerase Chain Reaction)
Blood typing

11. PCR (Polymerase Chain Reaction)
Developed in 1987
Amplify one molecule of DNA into billions of copies in a few hours
Identifies an individual based on microscopic amount of evidence
99% accuracy rate
Only one-tenth of a single percent of DNA (about 3 million bases) differs from one person to the next. Scientists can use these variable regions to generate a DNA profile of an individual, using samples from blood, bone, hair, and other body tissues and products.
In criminal cases, this generally involves obtaining samples from crime-scene evidence and a suspect, extracting the DNA, and analyzing it for the presence of a set of specific DNA regions (markers).
Scientists find the markers in a DNA sample by designing small pieces of DNA (probes) that will each seek out and bind to a complementary DNA sequence in the sample. A series of probes bound to a DNA sample creates a distinctive pattern for an individual. Forensic scientists compare these DNA profiles to determine whether the suspect's sample matches the evidence sample. A marker by itself usually is not unique to an individual; if, however, two DNA samples are alike at four or five regions, odds are great that the samples are from the same person.
If the sample profiles don't match, the person did not contribute the DNA at the crime scene.
If the patterns match, the suspect may have contributed the evidence sample. While there is a chance that someone else has the same DNA profile for a particular probe set, the odds are exceedingly slim. The question is, How small do the odds have to be when conviction of the guilty or acquittal of the innocent lies in the balance? Many judges consider this a matter for a jury to take into consideration along with other evidence in the case. Experts point out that using DNA forensic technology is far superior to eyewitness accounts, where the odds for correct identification are about 50:50.
The more probes used in DNA analysis, the greater the odds for a unique pattern and against a coincidental match, but each additional probe adds greatly to the time and expense of testing. Four to six probes are recommended. Testing with several more probes will become routine, observed John Hicks (Alabama State Department of Forensic Services). He predicted that DNA chip technology (in which thousands of short DNA sequences are embedded in a tiny chip) will enable much more rapid, inexpensive analyses using many more probes and raising the odds against coincidental matches.
PCR Analysis Polymerase chain reaction (PCR) is used to make millions of exact copies of DNA from a biological sample. DNA amplification with PCR allows DNA analysis on biological samples as small as a few skin cells. With RFLP, DNA samples would have to be about the size of a quarter. The ability of PCR to amplify such tiny quantities of DNA enables even highly degraded samples to be analyzed. Great care, however, must be taken to prevent contamination with other biological materials during the identifying, collecting, and preserving of a sample.

12. Some Interesting Uses of DNA Forensic Identification
ID 9/11 victims
ID plane crash victims
ID Missing children
DNA Shoah Project
Tomb of the Unknowns
Son of Louis XVI and Marie Antoinette
Nicholas Romanov
Peruvian Ice Maiden
African Lemba Tribesman
Super Bowl XXXIV Footballs and 2000 Summer Olympic Souvenirs
Study migration patterns
Poached animals
DNA banks for endangered species

13. Forensic Serology Antigen-Antibody reactions
Serum:The liquid that separates from the blood when a clot is formed. Blood clots when fibrin (a protein) traps and enmeshes the red blood cells.

14. Forensic Serology Antibodies secreted from b-lymphocytes
Serum:The liquid that separates from the blood when a clot is formed. Blood clots when fibrin (a protein) traps and enmeshes the red blood cells.

15. Blood
Artery
White blood cells
Platelets
Red blood cells

16. Blood
Plasma-55%
Buffy coat-<1%
Formed elements-45%

17. ANTIGENS

18. ANTIGENS b a b a b b a a b a b a b b a a

19. AGGLUTINATION

20. Blood being tested Serum Anti-A Anti-B Type AB (contains
agglutinogens A and B;
agglutinates with both
sera)
RBCs
Type A (contains
agglutinogen A;
agglutinates with anti-A)
Type B (contains
agglutinogen B;
agglutinates with anti-B)
Type O (contains no
agglutinogens; does not
agglutinate with either
serum)
Figure 17.16

21. Can this blood be associated to a particular individual?
MAYBE!?!
Assume that type O blood is found at the crime scene. Type O occurs in about 45% of Americans. If investigators type only for ABO, finding that the "suspect" in a crime is type O really doesn't reveal very much.
If, in addition to being type O, the suspect is a blond, and blond hair is found at the crime scene, you now have two bits of evidence to suggest who really did it. However, there are a lot of Type O blonds out there.
If you find that the crime scene has footprints from a pair of Nike Air Jordans (with a distinctive tread design) and the suspect, in addition to being type O and blond, is also wearing Air Jordans with the same tread design, you are much closer to linking the suspect with the crime scene.
In this way, by accumulating bits of linking evidence in a chain, where each bit by itself isn't very strong but the set of all of them together is very strong, you can argue that your suspect really is the right person.

22. Blood Type & Rh
How Many Have It
Frequency O
Rh Positive
1 person in 3
37.4%
Rh Negative
1 person in 15
6.6% A
35.7%
1 person in 16
6.3% B
1 person in 12
8.5%
1 person in 67
1.5% AB
1 person in 29
3.4%
1 person in 167
.6%

23. In Class Assignment Analyze 4 suspects blood types
Compare it to blood found on the murder weapon.
Determine the murderer.