Forensic DNA Testing


Forensics is defined as the study of evidence found at a crime scene and used in a court of law. Forensic DNA testing refers to DNA testing of evidence to convict or exonerate suspects based on their connection to that evidence. Just as fingerprints revolutionized crime fighting a century ago, forensic DNA testing has radically changed the way criminal evidence is examined.

Forensic DNA testing is a permanent feature now in the U.S. criminal justice system. It has freed the innocent from death row, it has cleared other convicts and suspects, and it has helped investigators solve seemingly unsolvable crimes. Even so, forensic DNA testing is partly a promise unfulfilled. There is still a backlog of evidence from unsolved cases that needs to be tested. Forensic DNA testing is used heavily in some states and almost not at all in others. Federal funding rules for forensic DNA testing encourage states to use the process on some cases but not others. Finally, lack of complete statistics have prevented a true evaluation of forensic DNA testing impact on justice so far.

Forensic DNA testing can be expensive. While many rape cases can be solved with DNA testing that costs about $500 per case, some murder evidence can cost upwards of $10,000 for forensic DNA testing. More complex than simple paternity testing, forensic DNA testing may need to call on several different methods depending on the type of evidence available, and whether or not the evidence as degraded or deteriorated in some way.

Forensic DNA testing is still a relatively young procedure. It was first used for law enforcement purposes in August of 1987 in England. Three months later, forensic DNA testing made its first U.S. appearance in Orlando, Florida. DNA testing as proven to be naturally suited for the criminal justice system. It is unique for every individual with little chance of misidentification. DNA is present in the types of evidence–like blood and semen–normally left at the scene of violent crimes.

One of the most recognizable computer tools seen on popular forensics TV shows is CODIS–the Combined DNA Index System. Launched by the FBI in 1992, CODIS is a super-database consisting of linked state DNA databases. The value of CODIS is based on the fact that some offenders, especially sex offenders, tend to repeat their crimes. By storing genetic profiles of convicted felons in a database, law enforcement officials have a chance to solve crimes by comparing DNA evidence collected at the crime scene to profiles in the CODIS database. CODIS has included databases from all 50 states since 1998.