Under this line of questioning, this case becomes a lesson of caution rather than a mere bungle, a warning that investigations driven exclusively by DNA evidence may lead us astray. It provides evidence of a kind of tunnel vision that is both extreme and systemic and demonstrates that—at least under some circumstances—DNA has come to trump other evidence and simple common sense and to serve as a teller of truth, a replacement for eyewitness identification, and a stand-in for an individual person or suspect.
More broadly, this case touches on a central question that this book seeks to answer: Has an increasing reliance on DNA in our criminal justice system furthered our pursuit of justice?
When DNA identification was first introduced into the criminal justice system in the 1980s, it was used in specific cases where DNA evidence had been obtained from a scene of a crime. An individual suspected of a crime would knowingly (and under a court-issued warrant) provide a DNA sample for comparison with DNA collected from the crime scene, and the results could be used as evidence to support his or her guilt or innocence.
The fact that no two people, with the possible exception of identical twins, share the exact same DNA sequence in their cells made DNA analysis an extraordinarily enticing tool for identification and surveillance. In the 1990s law enforcement in the United Kingdom and the United States began to permanently warehouse in data banks DNA taken from people who had been convicted of crimes. By generating a profile of the DNA that can be stored electronically, law enforcement can routinely compare a growing bank of DNA samples taken from offenders with DNA picked up at any crime scene. Anyone who had done wrong and had his or her DNA banked and went on to commit a second crime could be identified if his or her DNA was left behind. With the birth of DNA data banks, crime scenes have become a reservoir of biological trace materials like bloodstains, hair, semen, and skin cells from which DNA can be obtained and potentially matched with that of on-file suspects. Rapid developments in molecular genetics have made DNA analysis the fastest-growing forensic tool in criminal investigation since fingerprints were first introduced more than a century ago.
The last 15 years have witnessed an extraordinary expansion in the collection and storage of DNA by law enforcement. In the United States, state DNA data banks, initially limited to sexual offenders, have expanded dramatically so that today almost all states collect DNA from all felons, more than half from juveniles, and two-thirds from misdemeanants. States and federal agencies have adopted different criteria for human DNA data banking, resulting in a patchwork of standards for collection, retention, expungement, and access to and use of the information. Enthusiasm for DNA collection has prompted some state legislatures to expand their data banks beyond convicted offenders to include arrestees and other innocent individuals. By March 2010 over 8 million Americans have had their DNA forcibly collected and retained in a law-enforcement DNA data bank. Such collections have not been limited to the United States; many industrialized countries have established DNA databases of varying degrees of inclusion. In England children as young as 10 years old who are picked up by police for misdemeanors and petty theft have their DNA placed in the national data bank. Similarly, some U.S. states have collected DNA from teenagers. A few policy leaders, including former British prime minister Tony Blair, have called for a nationwide, universal DNA data bank in which everyone’s DNA would be collected and stored from birth.
As collections of DNA have expanded, so too have the ways in which DNA is used in criminal investigation. Initially DNA analysis was used by law enforcement to compare DNA from a suspect with DNA found at a particular crime scene. Today law enforcement is increasingly relying on DNA dragnets, where hundreds, if not thousands, of individuals living in the vicinity of a crime are pulled aside and asked to provide a DNA sample for purposes of exclusion. We have also witnessed an increasing use of “DNA profiling,” where genetic testing is used in an attempt to predict physical characteristics (eye color or hair color, for example) of a person whose DNA was left at the scene of a crime. In addition, law enforcement routinely picks up so-called abandoned DNA off coffee cups or cigarette butts left by individuals who are under suspicion without their knowledge or consent. Most recently the United Kingdom and some states in the United States have started to engage in “familial searching,” where police investigate family members of individuals in the database whose profiles are similar but not identical to that of DNA collected from a crime scene. These major changes in DNA data-banking laws and police practices have occurred with little, if any, public involvement.
The pursuit of justice involves more than simply the resolution and reduction of crime. Fairness, equality, and protection of basic civil liberties are as much a part of justice as are conviction and punishment of the guilty. If technology is to be used in the pursuit of justice, it should be used in ways that reflect a society’s commitment to maintaining privacy and autonomy, minimizing racial discrimination and injustices, and contributing to overarching fairness in the criminal justice system. The limitations, as well as the promises, of the technology should be appropriately defined and considered in decisions about the application of the technology to criminal investigation. Decision making should occur openly and with considerable public input. And resources dedicated to the technology should be consistent with other social priorities and human rights within and beyond the criminal justice system.
This book seeks to identify and define appropriate uses of DNA by law enforcement that will result in the furtherance of justice. Part I is largely descriptive and documents the history, applications, and expansion of the use of DNA in law enforcement. After a basic overview of the technology of forensic DNA typing (chapter 1), we trace the history and development of DNA data banking in the United States (chapter 2). We examine the current policy landscape, including the recent expansion of DNA data banks beyond individuals convicted of felony offenses to include arrestees, juveniles, misdemeanants, and individuals who voluntarily submit a DNA sample to exclude themselves as suspects in a crime. Part I also addresses the major ethical, sociopolitical, and legal concerns associated with increasing uses of DNA dragnets (chapter 3), familial searching (chapter 4), phenotyping of crime-scene DNA evidence (chapter 5), and the use of so-called abandoned DNA (chapter 6). We highlight sensationalized success stories that have served to foster dramatic expansions of DNA data banks and forensic DNA techniques. Part I also examines the use of DNA evidence in the exoneration of falsely convicted persons and, in particular, the impediments to using DNA evidence to prove innocence (chapter 7). We complete this part of the book with a discussion of the debate about the issue of universal DNA data banks, where the DNA of every citizen is taken and stored at birth (chapter 8).
Part II provides a transnational perspective on DNA data banking. We chronicle key trends in five other countries—the United Kingdom (chapter 9), Japan (chapter 10), Australia (chapter 11), Germany (chapter 12), and Italy (chapter 13)—and compare in particular the ways in which these governments have sought to balance privacy and other social and ethical considerations in creating, maintaining, and using DNA in solving crimes. We selected these particular systems because each case highlights some key differences in the ways in which industrialized countries have considered the dignity and rights of individuals in the establishment of a DNA-collection program. A comparison of the main features of each of these forensic DNA data-bank systems, as well as that of the United States, is provided in the appendix.
After tracing the expanding uses of DNA by law enforcement both in the United States and abroad, Part III provides the authors’ critical perspectives on society’s effort to balance personal liberty, privacy, social equity, and security in the development and use of forensic DNA technology. We examine the privacy (chapter 14) and racial justice (chapter 15) implications of DNA database expansions. We uncover the myth of infallibility, exploring places for contamination and error not only in extreme cases of the sort described earlier, but in those far less likely to
be righted (chapter 16). We analyze the efficacy of DNA data banking and question the prevailing assumption that “the more DNA, the better” (chapter 17). Finally, in the concluding chapter we propose that decisions about forensic uses of DNA be driven by a vision of justice that extends beyond crime and punishment and looks comprehensively at notions of privacy, autonomy, and fairness in the context of responsible criminal investigation (chapter 18).
Part I
DNA in Law Enforcement: History,
Applications, and Expansion
Chapter 1
Forensic DNA Analysis
DNA analysis is one of the greatest technical achievements for criminal investigation since the discovery of fingerprints. Methods of DNA profiling are firmly grounded in molecular technology.
—Committee on DNA Forensic Science,
National Academy of Sciences1
For those who can benefit from a primer on genetics and DNA profiles, this chapter reviews the nomenclature and genetic technology that form the basis of forensic DNA analysis. After a brief discussion of the basics of the genetic code, we explain such topics as DNA typing methods, short tandem repeats (STRs), and random-match probabilities. This chapter is designed for people who have very little background in molecular biology and forensic DNA analysis. Those who already possess this knowledge can proceed directly to chapter 2.
What Is DNA?
Deoxyribonucleic acid, or DNA for short, is the chemical in cells that specifies the composition of proteins and, along with other cellular components, contributes to their synthesis. DNA is also largely responsible for the inherited characteristics of organisms. The structure of DNA, as first postulated by James Watson and Francis Crick in 1953, is often compared with a spiral staircase or double helix with rungs or steps (see figure 1.1). The spine or backbone of the helix (analogous to the banister of the spiral staircase) consists of sugar-phosphate groups that link the steps of the spiral staircase and thus are constant throughout the length of the DNA strand for all individuals. The steps of the spiral staircase are composed of chemicals that are called bases or nucleotides. There are only four possible bases, adenine, guanine, thymine, and cytosine, denoted by the letters A, G, T, and C, respectively. The pattern or arrangement of these letters determines a person’s genotype, or genetic identity, as opposed to a person’s physical identity or phenotype (defined as the physical appearance or biochemical characteristics of an organism). No two people, with the possible exception of identical twins, have exactly the same series of letters that make up their DNA.
FIGURE 1.1. The double helix DNA structure. Left: A helixlike structure with two ribbons representing the sugar-phosphate groups and the horizontal steps or bases of the DNA molecule. Center: The hydrogen bond connecting complementary bases. Right: A model of a DNA molecule represented by a twisted lattice of spherical components. Source: From Modern Genetic Analysis by A. J. F. Griffiths, W. M. Gelbart, J. H. Miller, and R. C. Lewontin, ©1999, by W.H. Freeman and Company. Used with permission.
When a multicellular organism reproduces, it is the DNA within the reproductive cells (gametes or sperm and eggs) of the organism that serves as the template for the development of the fertilized egg. This fertilized egg develops into an organism of the same species, with species-similar but not necessarily identical physical (phenotypic) properties.
The complete set of human DNA is found in virtually every one of our cells (except the sperm and egg cells, which contain one-half of the DNA, and red blood cells, which have no nucleus), in every organ, and in our blood and immune system. DNA is found both in the nucleus of our cells and in the cell’s mitochondria (a component of the cell outside the nucleus that resides in the cytoplasm). The long, continuous nuclear DNA molecules are distributed on chromosomes, which also contain ribonucleic acid (RNA) and proteins. Humans have 23 pairs of chromosomes that are packaged in the nucleus of each cell. The DNA in the chromosomes is packed tightly, wound up and coiled into the nucleus of the cell. Proteins called histones help stabilize the tightly packed DNA within each chromosome.
Although DNA is thought to provide essential instructions for the functioning of our cells, it is not self-effectuating—it does not act by itself. DNA responds to prompts from the cell’s proteins, the body’s enzymes and hormones, RNA molecules, and sometimes external environmental factors. As Barry Commoner notes in “Unraveling the DNA Myth,” “Genetic information arises not from DNA alone but through its essential collaboration with protein enzymes.”2
Outside an organism, DNA can persist for many years under optimal conditions (see box 1.1). However, prolonged exposure to sunlight, warm temperatures, high humidity, and bacterial and fungal activities can result in DNA degradation. Some of the chemical enzymes released upon cell death may initiate the degradation of DNA. It is also more likely to degrade when it is on soiled rather than clean materials.
BOX 1.1 Brown’s Chicken Massacre and the Persistence of DNA Evidence
In 1993 seven people were ruthlessly killed in a robbery and left in two walk-in refrigerators at Brown’s Chicken and Pasta, a suburban Chicago restaurant. Collected from a trash can at the scene of the crime was a partly eaten dinner (two half-eaten chicken pieces). DNA testing techniques at that time were not sophisticated enough to produce any DNA profiles from traces of human saliva, so the chicken was frozen in hopes that developments in DNA testing would allow for future testing. Seven years later, that testing occurred, producing two DNA profiles. The profiles did not match any of the crime victims or suspects that police had at that time. Two years later, in 2002, a woman came forward with important details of the crime to police, including names of people who, she claimed, spoke about their involvement in the robbery. Police obtained a DNA sample from one suspect and matched it to a sample of saliva from the chicken dinner. A month later, Juan Luna and James Degorski were arrested and charged with the murders. Luna’s defense argued unsuccessfully that the DNA evidence against him should not be allowed because it had been mishandled over the years, including that it had been retested on multiple occasions and handled by scientists who acknowledged that they had not worn gloves. Both Luna and Degorski were found guilty of all seven counts of murder and were sentenced to life in prison.
Source: Authors.
What Is the Size of DNA?
If you uncoiled the entire nuclear DNA of a single human somatic cell (any cell other than sperm, egg, or red blood cells), holding the strands of the double helix end to end, its length would be about 2 meters (around 6 feet). The DNA is so thin and so tightly coiled that it can be this long but reside within the nucleus of the cell, which is about 5 millionths of a meter in diameter.
The length of a thread of DNA is usually measured in units called kilobases (kb). One kb is the molecular length equal to 1,000 base pairs of double-stranded DNA (there are two strands in the double helix), or 1,000 pairs of the bases (A, G, C, or T).
How many kilobases are there in the entire human genome? A human genome is made up of approximately 6 million kb (or 6 billion base pairs; see figure 1.1), 3 billion base pairs for each set of 23 chromosomes. To give some sense of this length, typing out the letters in a complete strand of our nuclear DNA would take up 57 million lines (where each line contained approximately 53 letters) and would fill about 1.2 million single-spaced pages.
Our DNA is distributed unequally among our 23 pairs of chromosomes. For example, chromosome 1, the largest human chromosome, has a length of 245,000 kb and would require 4.6 million lines of print or approximately 100,000 pages, while chromosome 22 of about 49,000 kb would require 925,000 lines of print or approximately 20,000 pages.
What Is a Gene?
A gene is usually defined as a segment of DNA that can be used by the machinery of the cell to synthesize a protein. In humans most of the genes are in the nucleus of the cell, dispersed across the 23 pairs of chromosomes (see figure 1.2). Genes can range in size from 100 bases (.1 kb) to as large as 2 million bases (2,000 kb). An average gene is a
bout 5,000 bases long (5 kb).
A gene located on one of a pair of chromosomes (a particular form of a gene or a noncoding DNA sequence is called an allele) may be the same but is not necessarily identical to that of its “copy” located on the other chromosome of the pair. One of the genes residing on a chromosome was contributed by the egg and the other by the sperm. A person can often be perfectly healthy with one “good” and one “defective” copy of a gene.
The totality of the DNA in an organism or cell is called its genome. The human genome can be thought of as a set of encyclopedias with 23 volumes, where each chromosome represents one volume. The DNA code comprises the text of those volumes, and the genes make up discrete chapters or paragraphs inside each volume.
The stretch of DNA on which the gene resides has more DNA than is required to encode a protein. The region of the DNA that is used to synthesize the protein is called the coding region (also called exon). The extraneous DNA on the segment, which is excised during the process of transcription (when the protein is being synthesized), is called the noncoding region (or the intron). To use the analogy of the page of text, imagine a sequence of letters (each representing a single nucleotide) such as AAGTACATATGAACAT. Suppose that the letters CAT represent the noncoding text (intron). When the gene is read and copied into a usable message for synthesizing a protein, the noncoding regions are removed, and the remaining segment in our example is AAGTA-ATGAA. This segment (representing the functional gene) is used to make a protein product.
Genetic Justice Page 2
