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Forensics: The Ties Between Science & Government



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What is DNA Forensics? Each species has a unique DNA sequence which can be identified by examination. In order to identify individuals, forensic scientists scan 13 DNA regions, called loci, which vary from person to person and then use that data to create a DNA profile of the individual, this is sometimes called a DNA fingerprint. There is an extremely small chance that another person has the same DNA profile for a particular set of 13 regions. In order for DNA Forensics to be effective, several matches (based on sequence or on numbers of small repeating units of DNA sequence) at many different locations on the person's genome must be found; one or two (even three) aren't enough to be confident that the suspect is the right one, but thirteen sites are used. A match at all thirteen is rare enough that you, a prosecutor or a jury can be very confident that the right person is accused if it is used to solve a crime. DNA found at the scene of the crime can be matched in one of two ways. The first requires obtaining DNA from a suspect and then seeing if it matches the DNA from the crime scene. Another method is comparing the DNA at the crime to DNA that has already been obtained, which is kept in the database CODIS. This science differs from others as its purpose is not to understand the universe and how it works but to understand what happened and who is responsible for what happened.

How is DNA Forensics used by the Government? Discovered in 1953, DNA was not used in government forensic testing until the late 1980s. At that time the federal government created the Combined DNA Index System, or CODIS. CODIS is a "system of national, state, and local DNA databases for the storage and exchange of DNA profiles" according a government created website. In order to optimize this system, all fifty states and the federal government require DNA samples to be collected from certain criminal offenders.

Is DNA Forensics a replacement for Eyewitness Testimony? According to the Dallas Bar Association, "mistaken eyewitness identification accounts for approximately 77 percent of post-conviction DNA exonerations." As a result, eyewitness testimony and identification are now more intensely scrutinized compared to previous decades. In some areas of the United States, eyewitness testimony must be evaluated based on the following properties before it may be used in the court room: Conversely the National Research Counsel declared “the reliability and validity of properly collected and analyzed DNA data should not be in doubt.” DNA analyses on saliva, skin tissue, blood, hair, and semen can now be accurately used to link criminals to crimes.
 * “the opportunity to view” (i.e., time, distance, lighting);
 * “the degree of attention of the witness” (i.e. passerby, complainant, trained officer);
 * “accuracy of description” (i.e. color, height, weight, hair, clothing, features);
 * “witness’s level of certainty” (i.e. how confident); and
 * “time between the crime and the confrontation” (i.e. time between the crime and the identification).

DNA Uses for Forensic Identification
 * Identify potential suspects whose DNA may match evidence left at crime scenes
 * Exonerate persons wrongly accused of crimes
 * Identify crime and catastrophe victims
 * Establish paternity and other family relationships
 * Identify endangered and protected species as an aid to wildlife officials
 * Detect bacteria and other organisms that may pollute air, water, soil, and food
 * Match organ donors with recipients in transplant programs
 * Determine pedigree for seed or livestock breeds
 * Authenticate consumables such as caviar and wine

Components of a Forensic Laboratory
 * Location:** Laboratories are commonly found attached to universities or in large police departments, others may be privately owned. Currently there are over two hundred laboratories in the United States.
 * Equipment:** The most up to date technology and techniques can be found in a forensic lab. There is equipment for everything from tracing fingerprints to DNA analysis equipment. Some labs may have separate divisions within the laboratory such as a Chemistry unit and Serology unit.
 * Components:**
 * Facial Reconstruction- this can be done by either a clay mold or by computer facial reconstruction
 * Dental Matching- x-rays taken from a victim can be compared to dental records which can aid in the identification process
 * DNA Testing (see below)
 * Blood Analysis- used to determine whether a substance found at the scene of the crime is blood or another bodily fluid as well as determine blood type
 * UV light- can be used to detect bodily fluids

Types of DNA Testing
 * Restriction Fragment Length Polymorphism- It was one of the first ways to analyze DNA, however due to the discovery of other more efficient techniques it is not used as often. This method requires cutting the DNA in specific sequence patterns which is done using restriction endonuclease. Then the fragments which vary in size undergo a process called Gel Electrophoresis in which an electric current is passed through the agarose gel. Since DNA is negatively charged when the current moves through the gel the DNA will begin to move across it with the smallest fragments of DNA moving the farthest. Eventually the DNA fragments will be separated and can be compared to the DNA that is being tested for a match.
 * PCR Analysis- Used to make copies of DNA that is impure or scarce and is quicker and more selective than any other method of DNA amplification. The process requires incubating DNA in a test tube with DNA polymerase, nucleotides and DNA primer. Then the DNA is briefly heated allowing the DNA to be copied, which can be repeated, producing billions of copies in a few hours.
 * STR Analysis- used to locate loci, this is used by the FBI because 13 different loci are used and can be imputed into CODIS
 * Mitochondrial DNA Analysis- used to examine DNA that cannot otherwise be analyzed
 * Y-Chromosome Analysis- used to trace relationships among men

Problems With DNA Testing
 * Backlogs of unanalyzed DNA samples- this occurs when there are too many DNA samples compared to the amount of people and machines working with the DNA. The backlogs can be from Casework Sample DNA (current cases) and Convicted Offender DNA (currently convicted people).
 * Not efficient enough- testing techniques can be time consuming
 * Requires additional training- there are not enough people trained to keep up with the amount of DNA that needs to be processed

How is the government dealing with these problems? Beginning in 2011, the National Institute of Justices combined the DNA Backlog Reduction Program and the Convicted Offender and/or Arrestee DNA Backlog Reduction Program into a single program. This merger helped to streamline the entire system and cut down on red tape in order to ensure that CODIS is able to operate more effectively and ultimately stop backlog from occurring. As far as its efficiency goes, scientific research concerning forensic DNA analysis is changing rapidly via the use of DNA chip technology, the advancement of more powerful methods of analysis, and the use of animal, plant, and microbial DNA. Under President Bush, "the Attorney General...develop[ed] training and provide[d] assistance regarding the collection and use of DNA evidence to the wide variety of professionals involved in the criminal justice system, including police officers, prosecutors, defense attorneys, judges, forensic scientists, medical personnel, victim service providers, corrections officers, and probation and parole officers."

Careers in Forensics: There are a vast amount of careers someone interested in forensics can pursue. The careers include but are not limited to those listed below. While each career is different they all work together to analyze evidence and put together the pieces of a crime, helping government officials to solve crimes and bring justice.
 * Forensic Latent Prints (Commonly portrayed on crime shows): job requires responding to crime scenes, and investigating and then collecting evidence such as finger prints, tire tread marks and footprints.
 * Forensic Entomology: although not typically hired by government agencies, the career requires being an expert at determining the age of insects found on the victim, which is a crucial part in determining when a crime has been committed.
 * Forensic Anthropology: deals with skeletal remains, with two goals in mind who is the victim and what happened to them, the only clue is the bones themselves.
 * Digital Forensics: traces computer activity, which can be used as evidence
 * Forensic Photography: documents the crime scene through pictures which record what can be seen at the crime scene and sometimes what can be missed at first
 * Forensic Serology: Analyzes DNA that is found at a crime

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Sources: http://www.justice.gov/ag/dnapolicybook_solve_crimes.htm http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml [|http://library.thinkquest.org/04oct/00206/index1.htm#] http://www.life.illinois.edu/molbio/geldigest/electro.html http://www2.dallasbar.org/members/headnotes_showarticle.asp?article_id=1428 http://www.councilforresponsiblegenetics.org/pageDocuments/H4T5EOYUZI.pdf http://www.forensiccareers.com/

Created by: Julie, Melanie, Shayla