1. Mike McCutcheon

2.  DNA, or Deoxyribonucleic Acid  DNA is examined from the cell nucleus  DNA is the building block for all life and is unique for every person.  Nearly every cell in a person’s body has a nucleus  The nucleus has 23 Chromosomes  100,000 genes in these chromosomes  Four chemical bases of DNA: Adenine, Guanine, Cytosine, and Thymine.  G always pairs with C  A always pairs with T  Over 3 billion base pairs

3.  DNA evidence can include:  Blood, saliva or saliva stains, liquid semen or semen stains, vaginal fluids, fingernails, hair (with root), skin cells, fingerprints, nasal and ear secretions, bones, sweat  In other words, DNA is everywhere.  You must know where to look for it and how to preserve it

4.  First report in 1868, but the structure was discovered in the 50’s  In 1984, Alec Jefferies, was able to map out DNA so that it could be compared to other samples  Restrictive Fragment Length Polymorphism (RFLP) was created and could discriminate to the certainty of 1 in 5 million  The problem was a large undegraded sample was needed  Because each cell only has one nucleus

5.  Polymerase Chain Reaction (PCR) was developed to solve the problem of needing a large sample  The scientist was able to copy the DNA structure creating enough genetic material to be tested  It allowed for much smaller samples, but he the statistical discrimination was much lower than the RFLP Some times the discrimination was not enough to make individual characteristics

6.  Short Tandem Repeat (STR)  Similar to the multiplication of the DNA in PCR, but with a much higher discrimination rate  1 in 6 billion  Saliva from licking a postage stamp has enough DNA material to make a distinct individualization

7.  In order for a lab to successfully examine DNA evidence, it is imperative that the samples be collected and stored properly.  Examples:  Gloves, Tyvek suits are a must, not a suggestion  Use sterile water  Air dry  Druggist fold  Use polyester swabs instead of cotton swabs  Properly packaged  Use adhesive tapes

8.  DNA can tell us many things:  Remember, it is only as good as what you can compare it to  Great care must be made to ensure that the sample is well protected.

9.  Mitochondrial DNA is not the same as DNA  Mitochondria are organelles that are in each cell.  The organelles exist in more numbers in each cell  mDNA is inherited only from the mother  It can be compared to any female relative  For example: Hair from a decomposed body can be compared to the mDNA of living relatives to see if there is a match  DNA needs the hair root. mDNA does not

10.  Has come a long way.  DNA can be extracted from a fingerprint  What is called “touch DNA”  Rapid growth of DNA databases through CODIS  Many states require those arrested/convicted to submit DNA to the CODIS database

11.  http://www.newenglandinnocence.org http://www.newenglandinnocence.org  http://www.nij.gov http://www.nij.gov  Gardner, R. (2012) Practical Crime Scene Processing and Investigation. 2 nd ed. CRC Press  http://www.guardian.co.uk http://www.guardian.co.uk