DNA for the Paralegal - Forensic DNA presentation including CSI them song, fade in text, med transition and DNA twisted pair slice background. Good for new paralegals and lawyers
16. What Are the Technologies Used in Forensic Investigation Restriction Fragment Length Polymorphism Polymerase Chain Reaction Short Tandem Repeat Michondrial Y-Chromosone
FORENSIC DNA FOR THE PARALEGALHi, I’m Martin, and I would like to speak about Forensic DNA. As paralegals, in the future you may cross paths with a case that requires knowledge of DNA evidentiary procedure. It may be criminal, family, and/or estate law.For those lucky enough to squeeze in time for quality television other than American Idol, you will find forensic shows like CSI, Forensic Files and others. On those shows we’ve been exposed to nomenclature and techniques. But what DO you REALLY NEED to know? Today we’ll just touch on the key things that will be important to us as paralegals.
FIRST AND FOREMOST, WHICH DNA?First and foremost, DNA is pronounced Deoxyribonucleic Acid, and it is the chemical inside the nucleusof all cells that carries the genetic instructions for making living organisms. Looking at it under a high powered microscope, a DNA molecule consists of two strands that wrap around each other to resemble a twisted ladder. It looks somewhat like the graphic on the right and the blue strand you will see on every slide today. You should know, not all DNA testing is alike. When I say that, I’m referring to the world of biotechnology vs. the world of forensic DNA. In the biosciences, when referring to DNA, we are discussing the atomic level structure and nucleotide chains. In forensic DNA, DNA profiling is used in identifying 13 distinct regions of a cell, then comparing those regions to a database of DNA profiles in the hopes of finding a match. There are no known cases where all 13 regions are the same in two people
WHEN IS FORENSIC TESTING REQUIRED?It is used identify potential suspects whose DNA may match evidence left at crime scenes.Exonerating persons wrongly accused of crimes. Identifying catastrophe victims such as in 9/11 and Hurricane Katrina.Establishing paternity and other familial relationships. Identifying endangered and protected species as an aid to wildlife officials.Detecting bacteria and other organisms that may pollute air, water, soil, and food supplies.Matching organ donors with recipients in transplant proceduresDetermining pedigree for seed or livestock breeds.And authenticating consumables and collectibles, such as expensive caviar, wines and even autographed footballs.
WHAT IS A DNA FINGERPRINT?First of all, you’ll hear different terms, profiling, testing, typing or genetic fingerprinting, ALL _ synonyms. Using a mass spectrometer to identify Saliva, Sperm, Blood, Hair, Skin Cells, or Human Tissue Samples, the “mass spec” as it is known, encrypts sets of numbers that reflect a truly unique DNA, hence, as unique as a fingerprint.
WHAT IS THE DNA DATABANK?CODIS is a computer software program that operates local, State, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons. Every State in the Nation has a statutory provision for the establishment of a DNA database that allows for the collection of DNA profiles from offenders convicted of particular crimes. CODIS software enables State, local, and national law enforcement crime laboratories to compare DNA profiles electronically, thereby linking serial crimes to each other and identifying suspects by matching DNA profiles from crime scenes with profiles from convicted offenders and is funded and managed by the FBI.The DNA Identification Act of 1994 formally authorized the FBI to operate CODIS and became fully operational in 1998. As of 2007, there were 5M DNA profiles and half million sample backlog profiles waiting to be entered.
HOW DOES FORENSIC IDENTIFICATION WORK?The FBI sets the standard that is used in all 50 states of the 13 marker match. One genetic marker, or LOCI, may have between four and forty different variations. There is a one in five billion chance of getting a match other than your own. DNA by far, is considered more reliable than the fingerprint or eyewitnesses. Eyewitnesses are considered a 50/50 in terms of accuracy and in the case of inter-racial eyewitnesses, much less than that.
WHAT ARE THE TECHNOLOGIES USED IN FORENSIC INVESTIGATION?In it’s simplest form, using a buccal swab isreduces the possibility of contamination. The DNA samples, depending on what they are and the technique, are deposited into a solution in a test tube, then separated and analyzed by a mass spectronic analyzer. The first of five tests listed, RFLP, is the first forensic DNA test applied as a standard and is no longer in use today. Using electrolysis, rather that a mass spec, it required samples the size of a quarter, rendering it useless in many instances. The following four are still used today. PCR, is one of the most popular methods because it can take a very small sample and reproduce in the power of 2. 2 gets 4, 4 gets 8, and so on and so forth. Once you test a sample, it cannot be tested a second time, so this test is very important when all you have is a minute sample and you need multiple tests. STR is chosen because of it’s ability to define each separate genetic marker region. As I said earlier, the legal standard set by the FBI requires a match of 13 genetic markers. Michondrial is used in cases where the sample is so mynute, that it cannot be sampled using other methods. Finally, with Y-Chromosome, this methodology tests the male chromosome, a process which identifies the father-son relationship.