The Current Effects of

DNA in forensic Criminology

in the 21st CenturyBy: Patricia Mitton

Definition

Forensic Biology- The Scientific analysis of biological evidence to provide objective information on legal matters or those that pertain to criminal and civil law

http://www.fbi.gov/publications/leb/2004/sept2004/sept04leb.htmhttp://www.dnaheritage.com/laboratory.asp

How is DNA used in Criminal Investigations?

http://www.pierce.ctc.edu/proftech/crimJustice/degrees/forensicTech.php

Current Method: DNA TypingProcess

• requires detection and screening of biological evidence

•DNA extracted from a specimen and using PCR amplifies specific regions of DNA

•PCR used to determine a DNA profile

Reason

•to obtain a DNA profile to be compared with suspects, victims, and database samples’ profile’s in order to find a match and catch the perpetrator

STR TypingSTR (short tandem repeat) Typing• Done today using capillary- based electrophoresis or gel

electrophoresisInvolves:1. Extraction of DNA2. Amplification via PCR 3. Separation of PCR products according to length4. Detection via staining or fluorescent dyesPros • Currently the standard DNA typing technology in 11 different

countries• Gives strong, accurate evidence to present in a court caseCons• Mutations have been found to occur while amplifying with PCR such

as nucleotide insertion, deletions or repeats of one or more elements• Need certain amount of DNA(250 picograms) in order to carry out

necessary amplification

STR DNA typing• Used today using capillary-

based, gel electrophoresis

• Focuses on specific region of DNA

• Look for similarities in band patterns to match suspects to the victim

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802002000300004

New Forms of DNA Typing

LCN (Low Copy Number) Typing

• Still uses STR typing but requires less DNA to amplify

• Allows for analysis of small amounts of sample found on evidence such as a gun handle or doorknob

• Method allows for larger chance of mutations

mtDNA (Mitochondrial

DNA) Typing

• Easier to type from small and/or degraded samples because it exists in multiple copies

• Can analyze biological samples that lack a DNA nucleus such as hair, bones and teeth

• Has been successfully typed however there is controversy about interpretation of results

http://www.dnajunction.com/technology/mtdna.php

SNP (Single Nucleotide Polymorphism) Typing

• Can be typed accurately, cheaply and in large volumes

• Avoid many mutations while processing

• Several SNPs lie on same chromosome which cause problems for relatedness in large pedigrees

http://eli-nati.fletzet.com/gallery2/main.php?g2_view=core.ShowItem&g2_itemId=76758

Microbial Forensics: BiocrimesAbout Bio crimes:

• Perpetrators of bio terrorism use pathogens or toxins as weapons

• Low cost for producing pathogenic agents in criminal acts

• Microorganisms and their toxins major bio weapon used because can be grown via single organism or cell

• Bio terrorism will be one of major threats of 21st century

How to stop Bio Crimes:

• Development of a strong, scientifically based microbial forensics program

• Determine procedures for collecting microbial samples at the crime scene

• Come up with a system when a suspected bio terrorism attack is underway

• Learn more about virus’s in nature and where they come from so that we can discover more about genetically engineered virus’

Biocrimes• An example of a biocrime is the

anthrax attack of 2001 caused by spores of the bacterium Bacillus Anthracis.

• Hundreds of people were infected and five people died.

http://www.officeroutlook.com/news/Science/1286.htm

http://webs.wichita.edu/mschneegurt/biol103/lecture20/anthrax_pustule.jpg

http://microbes.historique.net/images/anthrax2.gif

Future Outlook1. Better equipment and accurate machinery for the use of DNA

typing and amplification.

2. The use of SNPs and micro- array technology are looked at to hopefully be major fundamental tools for the analysis of small, degraded samples found at crime scenes with few mutations or problems

3. More developed DNA databanks which store biological samples from crime scenes.

http://science.nasa.gov/headlines/y2004/10sep_radmicrobe.htmhttp://www.cmbi.kun.nl/mcsis/vanhamer/introduction.html

Resources1. _______.(Nov.30,2007).DNA Forensics. Retrieved on December 15,2007 from <http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml>

2. Balding, David J. (2005). Weight-of-evidence for Forensic DNA Profiles. John Wiley and Sons, Ltd.

3. Ricciuti, Edward. (2007). Science 101- Forensics. New York: Smithsonian.

4. Brunette, Stephen A.(2007)”Forensic Evidence” Retrieved on Wednesday Jan. 2, 2008 from http://www.accessscience.com/content.aspx?id=757566#BIB

5. Breeze, Roger G. (2005). Microbial Forensics. London, UK: Elsevier Academic Press.

6. Norah Rudin, Ph.D. (2002). An Introduction to Forensic DNA Analysis. New York: CRC Press.

7. Safterstein, Richard.(2004).Criminalistics:An introduction to Forensic Science. New Jersey: Pearson Education, Inc.

8. Salyers, Abigail A.(Jan. 2004).Microbial Forensics. Retrieved on December 16, 2007 from <http://www.actionbioscience.org/newfrontiers/salyerspaper.html>

9. Steven Lee, "Forensic DNA testing.” (2007).Retrieved on Wednesday Jan. 2, 2008. from <http://www.accessscience.com/content.aspx?id=YB060160>