How has our knowledge of DNA improved the study of criminal forensics?

Introduction

Through genetics, the study of DNA, we are able to figure out what and how genes are responsible for many things like our hair color or why do some people look a lot like their parents and others don’t. It also allows us to understand better how species evolve and how are they related to each other. It is important to understand how DNA mutates, changes and replicates in order to get information about what mechanisms cause DNA to change.

In the 1970s scientists developed a DNA sequencing technique and other methods to manipulate and analyze DNA. This gave them the basic tools to start exploring the DNA blueprint which provided the techniques for a vast international project called The Human Genome Project (MRC). The Human Genome Project which was a major international project with the goal of decoding all our genetic information by 2003. A rough draft was done in June 2003 and it was a huge milestone that helped us understand how our genes can determine who we are (Genome Project). Many of today’s advances in DNA and biotechnology allow scientists and medical doctors to potentially cure genetic disorders through gene therapy by inserting, deleting or manipulating genes (Tillery, page 686). Another use of DNA technology is the creation of mutation by transferring DNA from one organism to another through techniques like cloning and introducing new DNA sequence into an organism to alter their genetic makeup (Tillery, page 683). Other uses of DNA technology is genetic fingerprinting which makes possible to show the nucleotide sequence differences between individuals since no two people have the same nucleotide sequences. (Tillery, page 688)

DNA in forensic science
I would like to focus on the impact that DNA technology had on the field of forensic science and how the discovery of DNA is used nowadays in the criminal justice system to identify criminals and to exonerate the innocent. Each human being contains a copy of DNA that allows analysis to be performed on samples of hair, skin, blood, sweat, saliva and semen. Forensics scientists used the DNA in those samples found in a crime scene in order to identify a matching DNA of an individual. This process is called “DNA profiling” but it may also be called “genetic fingerprinting”. We can use DNA analysis to identify an individual because about 0.1% of human genomes differ from others (Lyle 2005).
DNA Profiling and the Polymerase Chain Reaction
In 1984 an English geneticist, Alex Jeffreys of the University of Leicester developed DNA profiling, which was later used in 1986 to exonerate an innocent man and then led to the arrest of a rapist and murderer in the Enderby murders cases in England (Lyle 2005). Another important event that helped the advancement of DNA use in forensic sciences was the Polymerase Chain Reaction. In 1983, Kary B. Mulis developed the Polymerase Chain Reaction which is sometimes called “Molecular photocopying”. This technique helped the progress of DNA technology because before its development, the available methods used to amplify or generate copies of recombinant DNA fragments were time-consuming and labor-intensive (Encyclopedia Britannica). In contrast, PCR is a fast and inexpensive technique used to amplify small segments of DNA so that it can be analyzed by scientists. The process requires the DNA specimen, free DNA nucleotides, synthetic “primer” DNA, DNA polymerase, and simple lab equipment such as a test tube and a source of heat. To amplify a segment of DNA using PCR, the sample is heated so the DNA separates into two pieces of single-stranded DNA. Then an enzyme builds two new strands of DNA using the original strands as templates. Then each of these strands can be used to create new two new copies and so and so on (Genome Project).
DNA in the Criminal Justice System
In 1994, in the United States the DNA Identification Act gave the FBI the authority to start a national DNA index to assist with solving crimes and the National DNA Index System (NDIS) began operating in 1998. Nowadays, the NDIS is the highest level of the three-tiered Combined DNA Index System known as CODIS. All 50 states have passed legislation mandating that DNA profiles of particular convicted offenders be sent to CODIS. Currently the database has more than a million entries in its Convicted Offender Index and 50,000 profiles collected form crimes scenes that have not been matched to any specific criminal (Lyle 2005).
The new development of DNA technology and the ability of getting genetic matching on small samples of blood, skin, saliva or hair have led to many cases being re-opened. The Innocence Project is a nonprofit group dedicated to post-conviction DNA testing and they keep the number of exonerated people constantly updated in their homepage: www.innocentproject.org. As of February 2014, their website stated that DNA testing had absolved 312 people from wrongful convictions (The Innocence Project).
Since it was first introduced in 1985, DNA fingerprinting has solved crimes that were considered unsolvable, identified remains of unidentified bodies, establish paternity cases and absolved wrongly accused individuals. It has become an indispensable tool in fighting crime because it provides unambiguous identification of a criminal from miniscule traces of biological material left at a crime scene. Like in the case of fingerprints, an exact DNA fingerprint match does not amount to proof of guilt. We must also note that DNA profiling is used to identify victims of natural disasters like Hurricane Katrina, as well as positively identifying bodies or body parts in serious accidents and to identify individual victims in war acts like in the attacks of the World Trade Center on September 2011 (Lyle 2005). It is also critical when identifying victims in difficult cases where the victim's condition is unrecognizable to family or friends.

Potential issues with DNA evidence
DNA evidence is not exempt of mistakes. There can be errors when collecting or handling the DNA samples, and that can have great consequence when using such evidence to either point to an innocent person as a suspect or exonerating a guilty person from a crime. There is also the possibility that someone tampers with the evidence in the lab either on purpose or by negligence. Another potential problem could be the degradation of DNA samples which occurs when a sample breaks into small units due to microbial or environmental causes like temperature, humidity, sunlight and exposure to chemicals. In addition to these possible errors, DNA testing can be expensive and most DNA testing done by labs for court trials can cost around $1,500 (PBS).
Conclusion
DNA evidence is very easy to obtain since it is present in every cell in our bodies. These traces are can be used to identify us and link us to places where we have been. Through the use of modern technology, the amount required of DNA for analysis is miniscule in criminal cases is minimal. However, forensics is still being developed and is not fool proofed. A “confirmed match” does not always supply concrete proof of guilt. Hopefully through the advancement of technology we might reach a point where we can develop a foolproof form of human identification that would allow our criminal justice system to be 100% sure before convicting someone of a crime.

Bibliography and References

“All about the Genome Project” (11 July 2013).
National Human Genome Research Institute
Retrieved from http://www.genome.gov/10001772

Amanda Lyle & Michael J. Harris (7 November 2005). “DNA forensics”
BioWorld, a publication of the Daily Biopharmaceutical News Source.
Retrieved from http://www.bioworld.com/content/dna-forensics

“DNA research”. Medical and Research Council, Achievements and Impact
Retrieved from http://www.mrc.ac.uk/Achievementsimpact/Storiesofimpact/DNAresearch/index.htm

Encyclopedia Britannica Online. “Polymerase Chain Reaction”
Retrieved from http://www.britannica.com/EBchecked/topic/468736/polymerase-chain-reaction

Jane Siegel & Jonathan H. Oberman. (27 February 1997). “Frequently asked Questions”
PBS Channel, Frontline episode “What Jennifer Saw – examining eyewitness error in crimes and how DNA evidence is setting the innocent free”.
Retrieved from http://www.pbs.org/wgbh/pages/frontline/shows/dna/etc/script.html

Tillery, Bill. (2011).
“Integrated Science”, 5th Edition.

The Innocence Project.
Retrieved from www.InnocenceProject.org

Randy James. (19 June 2009). “A brief history of DNA Testing” Time Magazine.
Retrieved from http://content.time.com/time/nation/article/0,8599,1905706,00.html

William C. Thompson. (5 November 2008). “The potential for error in forensic DNA testing”
Magazine “Genewatch” from the “Council for responsible genetics”
Retrieved from http://www.councilforresponsiblegenetics.org/GeneWatch/GeneWatchPage.aspx?pageId=57