What is DNA in a forensic context?
At the molecular level, forensic DNA is “junk DNA.” By this, we mean that it is DNA that has no known coding function for the determination of a physical trait such as eye or hair color. Forensic DNA is “non-coding,” highly variable, and statistically consistent in frequency among various individuals. Thus, by analyzing nine DNA systems, a unique DNA profile can be determined to the power of one in several billion. Forensic DNA can be extracted from “trace” evidence and subsequently analyzed using a process called polymerase chain reaction (PCR). PCR is the process of “copying” or amplifying very small sections of DNA within biological evidence in order to obtain the quantity of DNA required for analysis. PCR enables extremely small samples and very old, degraded samples to be analyzed. DNA evidence can be extracted from items such as a licked envelope, Kleenex tissue, toothbrush, cigarette butt, used syringe, blood splatter or chewing gum, and even dandruff. DNA analysis has applicati
