Biological ForensicsBiological Forensics

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.

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

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

http://www.rit.edu/~vjrnts/forensics/labs/lab1/lab1pix.html

Categories of Forensics

• DNA Evidence

• Forensic Entomology

• Forensic Serology

• Forensic OdontologyBluebottle blow fly

Fingerprint counting number of typica

• Forensic Fingerprinting

• Forensic Anthropology

• Forensic Art

Radiocarbon dating of the Dead Sea Scrolls

Composite art, image modification, age progression, post-mortem reconstruction and demonstrative evidence

• Forensic Pathology• Forensic Psychiatry• Forensic Toxicology• Bloodstain Pattern

Analysis• Forensic

Photography

Biological Forensics

Use of Entomology(the study of insects)

Use of Molecular biology(DNA analysis)

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.

Two main methods of Molecular Forensics

• PCR (Polymerase Chain Reaction)

• Blood typing

PCR (Polymerase Chain Reaction)

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

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

• Antigen-Antibody reactions

Forensic Serology

• Antibodies secreted from b-lymphocytes

Forensic Serology

White blood cells

Platelets

Red blood cells

Artery

Plasma-55%

Formed elements-45%

Buffy coat-<1%

ANTIGENS

ANTIGENS

a

a

a

a

a

a

a

a

b

b

b

b

b

b

b

b

AGGLUTINATION

Figure 17.16

SerumAnti-A

RBCs

Anti-B

Type AB (containsagglutinogens A and B;agglutinates with bothsera)

Blood being tested

Type A (containsagglutinogen A;agglutinates with anti-A)

Type B (containsagglutinogen B;agglutinates with anti-B)

Type O (contains noagglutinogens; does notagglutinate with eitherserum)

Can this blood be associated to a

particular individual?

MAYBE!?!

Blood Type & Rh How Many Have It Frequency

O Rh Positive 1 person in 3 37.4%

O Rh Negative 1 person in 15 6.6%

A Rh Positive 1 person in 3 35.7%

A Rh Negative 1 person in 16 6.3%

B Rh Positive 1 person in 12 8.5%

B Rh Negative 1 person in 67 1.5%

AB Rh Positive 1 person in 29 3.4%

AB Rh Negative 1 person in 167 .6%

In Class Assignment • Analyze 4 suspects blood types

• Compare it to blood found on the murder weapon.

• Determine the murderer.