Prior to the 1980s, courts relied on testimony and eyewitness accounts as the primary source of evidence. Notoriously unreliable, these techniques have since faded due to the extraordinary reliability of forensic DNA analysis. In 1984, British geneticist Alec Jeffreys of the University of Leicester discovered an interesting new marker in the human genome. Most of the DNA information is the same in every human, but the junk code between genes is unique to each person. Junk DNA used for investigative purposes can be found in blood, saliva, sweat, sexual fluids, skin tissue, bone marrow, dental pulp, and hair follicles (Butler, 2011). By analyzing this junk code, Jeffreys found that some sequences of 10 to 100 base pairs repeated multiple times. These tandem repetitions are also the same for all people, but the number of repetitions is highly variable. Before this discovery, a drop of blood at a crime scene could only reveal a person's blood type, as well as some proteins specific to some people. Now forensic DNA analysis can reveal a person's gender, race, susceptibility to disease, and even propensity for high aggression or drug abuse (Butler, 2011). More importantly, the certainty of DNA evidence is extremely powerful in court. Amazed by the near-perfect accuracy of this technology, the FBI changed the name of its Serology Unit to the DNA Analysis Unit in 1988 when it began accepting requests for DNA comparisons (Using DNA to Solve Crimes, 2014). There are thirteen standard tandem repeats used in modern forensics and together these sequences create a DNA profile. Except in the case of identical twins, the probability that two people will have the same genetic code at all thirteen fundamental loci is less than one in a trillion (Jones, 2004). Investigators compare these... half of the document......d Beyond." Forensic Magazine. Web. May 29, 2015. http://www.forensicmag.com/article/dna-forensics-rflp-pcr -str -and-beyond (Fall 2004). Using DNA to Solve Crimes." -dna-solve-crimesSachs, Jessica Snyder DNA AND A NEW KIND OF RACIAL PROFILING 2004http://www.popsci.com/scitech/article/2004-. Wallace, AR Jacksona, J. Gruberb, AD Thibedeaub Forensic DNA Databases – Ethical and Legal Standards, ScienceDirec, 2014.http://www.sciencedirect.com. /science/article/pii/S2090536X14000239Westphal, Sylvia Pagán links drugs to its source Daily News, 2003https://www.newscientist.com/article/dn3919-dna-profiles-link-dope-to-its-source./