ty of substances, for example, hair, saliva, cigarette butt, perspiration in a hatband, bone, skin cells, blood, and fingernails, to list a few (Fisher 233). DNA is a powerful tool because each person's DNA is different from every other individual, with the exception of identical twins. The chance that two individuals can have the same DNA is one in hundreds of billions, which means that each strand of DNA is like a unique "fingerprint" for each person. A computer is used to compare DNA profiles and can then generate a number called "a statistical probability" that two samples match. The larger the probability, the more likely the suspect is the criminal (DNA Technology 28 -45).
             Forensic DNA typing is a science that has been in use for approximately 17 years now. It was first used in casework in 1985 in the United Kingdom. DNA typing was initiated in the United States in late 1986 by several commercial laboratories and then in 1988 by the Federal Bureau of Investigation (FBI). Forensic DNA typing is now commonly used by dozens of state and local crime laboratories in criminal investigations. The first use of DNA as evidence in a criminal proceeding was in Florida in 1988 and was admitted in 1990 at the federal court level (Wickenheiser 443). As with any new scientific technique that is introduced into court, legal challenges abound. There are two legal tests that can be used to determine whether scientific tests are admissible in court, and depending on the jurisdiction in which a case is heard, the Frye test may be used (Fisher 233).
             The Frye rule comes from a 1923 federal case wherein the court stated: Just when a scientific principle or discovery crosses the line between experimental and demonstrable is difficult to define. Somewhere in this twilight zone, the evidential force of the principle must be recognized, and while the courts will go a long way in admitting expert testimony deduced from well-recognized scientifi...