Background
Prior to the mid-1980s, crimes were solved by criminal investigators who compared evidence collected from crime scenes to known or suspected offenders. Evidence commonly consisted of fingerprints, hair, teeth marks, blood or semen samples, and fingernail scrapings. Fingerprints were often considered by investigators to be the best lead for the identification of a suspect and for connecting the suspect to the crime scene. Fingerprints are unique markers to an individual, but they have limited value in impacting crime because they can be altered through surgery. Evidence such as hair, teeth marks, blood, and semen likewise suffer in their ability to convince juries to the standard of ”beyond a reasonable doubt” because their uniqueness is subjective. In many criminal cases it can be shown that a suspect’s hair or blood type was similar to that found at a crime scene, but not to the exclusion of all other hair or blood. A paradigm shift occurred in the mid- to late 1980s that changed the way criminal investigators impact crimes. The change was the result not of the type of evidence collected but, rather, of the way the evidence was forensically examined.
DNA and the Criminal Identification Process
Sir Alec Jeffreys and associate Victoria Wilson successfully proved in 1985 that in the DNA (deoxyribonucleic acid) of human beings, ”hypervariable” regions that they called ”minisatellites” exist in which core sequences of DNA repeated (Jeffreys, Wilson, and Thein 1985). They determined that the repetitive sequences were unique to each individual (except in the case of identical twins), and thus the term ”DNA fingerprinting” was born.
For forensic criminologists, this discovery was monumental. They knew that if they could examine evidentiary samples from crime scenes that contained nucleated cells left by a perpetrator, they would have a basis on which to build a case that would be more unique to an individual than previous evidence such as fingerprints. In essence, this discovery could be deemed as genetic fingerprinting. Since much of the evidence left at crime scenes includes nucleated cells, including hair follicles, semen, white blood cells, saliva, and perspiration in the ridges of fingerprints, it was widely thought that crimes would be easier to solve. The effectiveness of forensic evidence, however, is limited by the proper collection, storage, and analysis of the evidence.
Criminal Justice Application of DNA Fingerprinting
Police agencies, through their regional or state crime labs, submit crime scene DNA profiles for inclusion in the national DNA database CODIS (or combined DNA index system). Following a pilot database program in 1990, the CODIS database became effective in 1994 and is maintained by the Federal Bureau of Investigation. The CODIS database contains both crime scene DNA samples and DNA from known offenders. Officers from local law enforcement agencies run queries on the CODIS database based on crime scene evidence. When a match is made between evidentiary DNA and a DNA profile in CODIS, the match is known as a ”hit.” According to the CODIS information website maintained by the FBI, there were 119,782 forensic files and 2,643,409 offender profiles housed in the National DNA Index System as of November 2005. As a measure of success, the FBI reports that the CODIS database has ”produced over 25,900 hits assisting in more than 27,800 investigations” (Federal Bureau of Investigation 2005).
Criminal justice agencies use DNA fingerprinting in the course of their duties in various ways. Consider for a moment that the attacks on the World Trade Centers on September 11, 2001, constituted the largest crime scene in the history of the United States. DNA fingerprinting was used to identify perpetrators and victims of that crime. DNA fingerprinting is also used to identify human remains in other disasters, such as airplane crashes. A growing field of concern and study for criminal justice agencies concerns missing children and adults. DNA fingerprints are used not only by criminal prosecutors to identify offenders but also by prosecutors and defense attorneys to aid in the exclusion of specific people as suspects in specific cases. Although the absence of DNA samples from seminal fluids in a rape case does not mean that a suspect did not commit the offense, the presence of such evidence could exonerate a suspect if it does not match that of the suspect. As of November 2005, the Innocence Project reports that 163 people have been exonerated of crimes they had previously been convicted of after postconviction DNA sampling was conducted on their behalf (Scheck 2005).
Because DNA samples can be obtained from a wide variety of evidentiary sources, police officers are trained in ever-changing methods of collection and preservation of crime scene evidence. For example, it was once thought that evidence should be preserved in plastic bags. The common practice in use today is to place dried samples in paper bags so that contamination or degradation of the evidence is not facilitated due to the development of moisture. Additionally, the amount of evidence necessary in order to collect a usable DNA sample has decreased due to new technologies and methodologies in the processing of DNA. Crime labs nationwide are increasingly becoming certified to handle and process DNA evidence using industry-accepted protocols. Uniformity in the handling and processing of DNA samples helps to ensure judicial acceptance of the evidence when presented in criminal cases.
Issues Facing Law Enforcement
As the probability of discovering DNA evidence left by a suspect at a crime scene increases, so too does the demand for the storage and processing of evidence. Police agencies, in anticipation of someday clearing reported crimes through the matching of DNA fingerprint profiles from evidence to those housed in CODIS, are forced to create additional storage space for crime scene evidence. Frustration mounts as officers wait for results of DNA analysis from crime labs that have been inundated with extremely high numbers of requests for analysis. A recent National Institute of Justice study conducted by researchers at Washington State University, in cooperation with the law firm Smith, Alling, Lane, P.S., reported that state and local crime laboratories claimed they maintain more than 57,000 unanalyzed DNA cases (Lov-rich et al. 2003). The backlog was attributed to the lack of manpower to conduct DNA analysis. In addition, the researchers discovered that there are more than half a million cases nationwide in which DNA evidence could exist but has not yet been submitted to the crime lab for analysis (Lovrich et al. 2003).
Many people involved in the criminal justice system agree that increasing the volume of DNA fingerprint analysis at various crime labs and the inclusion of such analyses in massive databases such as CODIS will improve the quality of life in the United States by making the identification of offenders quick and certain. Others, however, argue that the improvement in DNA fingerprinting technology may lead to the restriction of personal liberties.
Legal Challenges
Among the questions surrounding the inclusion of DNA fingerprint profiles are, Which profiles are to be included, and which are not? Are the DNA fingerprint profiles of misdemeanants to be included, or only those of felons? Which felonies qualify for inclusion, violent only or nonviolent also? How long are the profiles to be maintained in the database? Are they to be purged upon the completion of the corresponding prison sentence by the offender? When are the profiles to be collected? Are they collected and entered into CODIS on conviction, on prison entrance, or on exit?
All of those questions have been the basis of lawsuits filed by civil libertarians. On a more technical note, concerns about near misses have sounded with respect to disclosure of a match probability when a suspect in a criminal action has a sibling who has not been excluded as a possible suspect (Buckleton and Triggs 2005). To summarize the argument, it is contended that when a crime lab returns the results of DNA fingerprinting, an obligation is owed that goes beyond simply making notification that a suspect’s DNA fingerprint is or is not the donor of origin. If possible, the argument goes, crime labs should make notification if a relative of the suspect is the donor.
Future of DNA Fingerprinting in Criminal Justice
Legal wrangling surrounding the collection, preservation, and analysis of DNA evidence and the presentation of DNA fingerprints as unique personal identifiers will highlight criminal justice forensics during the next few decades. Criminal justice agencies and crime laboratories will adapt to newly defined protocols as the demand for improved DNA fingerprint profiling increases. Crime labs will continue to need increased funding to meet the ever-increasing demands placed on them by the law enforcement community. New discoveries in the methodology of DNA fingerprint analysis will put additional pressure on the FBI’s CODIS database to improve in both capacity and classification capability. As DNA fingerprint typing becomes more prolific due to improved methodologies and as the CODIS database capacity increases in numbers of both crime scene profiles and offender profiles, the ability of law enforcement to impact crime should increase.
