Relative doubt: familial searches of DNA databases.

Author:Murphy, Erin E.

The continued growth of forensic DNA databases has brought about greater interest in a search method known as "familial" or "kinship" matching. Whereas a typical database search seeks the source of a crime-scene stain by making an exact match between a known person and the DNA sample, familial searching instead looks for partial matches in order to find potential relatives of the source. The use of a familial DNA search to identify the alleged "Grim Sleeper" killer in California brought national attention to the method, which has many proponents. In contrast, this Article argues against the practice of familial searching on a variety of grounds, including claims related to equality, accuracy, privacy, racial discrimination, and democratic accountability. It then addresses the legality of the method. Lastly, in the event that arguments to prohibit the practice prove unpersuasive, this Article sets forth recommendations for restrictions on familial searches that might ameliorate their possible iniquitous effects.

TABLE OF CONTENTS INTRODUCTION I. A BRIEF INTRODUCTION TO FAMILIAL SEARCHING A. Forensic DNA: Mechanics B. Familial Searching: Mechanics C. Current Landscape II. SHOULD WE ALLOW FAMILIAL SEARCHES? A. Actual and Apparent (Non-Race-Based) Discrimination B. Accuracy C. Privacy 1. Databased Persons 2. Innocent Relatives 3. The Source D. Societal Interest in Intact Families E. Actual and Apparent Ethnic and Racial Discrimination F. Preserving Democratic Accountability over the Proper Scope of Databases G. Conclusion 1. A Word About Actual Efficacy 2. A Word About Universal Databases III. CONSTITUTIONALITY A. Equal Protection B. The Fourth Amendment IV. POSSIBLE PARAMETERS A. What Legal Form Should Familial Search Guidelines Take? B. Should Different Standards Govern Intentional and Fortuitous Partial Matches? C. When May Familial Searches Occur? D. What Should Be the Technical Parameters Delimiting the Scope of the Search? E. Which Databases May Be Searched? F. What Regulation Is There of the Follow-Up After a Potential Familial Match? G. What Structural Oversight Exists? CONCLUSION INTRODUCTION

In 2005, Denver District Attorney Mitchell Morrissey recovered DNA profiles in three separate unsolved rape cases, but his search for matching profiles in the national DNA database failed to return any hits. (1) Typically, such a search looks for complete identity between a crime-scene sample and a known offender using thirteen genetic markers. However, the software that compares profiles can reveal not only exact matches, but also near-miss matches of fewer markers. In Morrissey's case, each of the three searches also uncovered partial matches. Because genetic information is inherited, Morrissey conjectured that those profiles might belong to relatives of the sources, and thereby point to the perpetrators of the offenses.

The only problem was that the matches originated in Oregon, Arizona, and California, and the Federal Bureau of Investigation ("FBI"), which administers the national database, stores its information anonymously. Even though a state can always access its own information, FBI rules forbade states from disclosing to other states the identifying information of anyone other than the "putative perpetrator." When Morrissey asked for an exemption, federal DNA database head Thomas Callaghan refused, citing concerns about privacy and fairness. (2) He worried that the searches would discredit DNA databasing efforts, and stated that he "would be more comfortable with congressional authorization to conduct familial searches.'' (3)

Frustrated, Morrissey wrote to the director of the FBI laboratories in 2006, complaining that the policy "protects murderers and rapists" and warning that one of his "quite assertive" victims would generate a media maelstrom. (4) Several days later, FBI Director Robert Mueller called Morrissey to discuss the issue. Shortly thereafter, Director Mueller changed the national database regulations to permit the release by states of identifying information in the event of a partial match, defined as one allele at each locus) Arizona and Oregon then complied with Morrissey's request, but California still resisted. After a campaign by the state's sheriffs and district attorneys' organizations, however, California Attorney General Jerry Brown agreed to release the name. Then, in April of 2008, Brown announced that California would not only share such information, but would also set out the first policy in the nation that explicitly authorizes intentional searches for partial matches--also known as "familial" or "kinship" searches--in its DNA databank. (6) Additional jurisdictions have since then formally announced their intention to begin conducting familial searches, (7) and individual laboratories have simply conducted such searches even in the absence of formal legal authorization or express policies. (8)

Interestingly, often lost in recitations of Morrissey's crusade is one revealing fact: his familial searches did not work. None of the three matches turned out to point toward a relative, much less the source, of the actual crime-scene sample. (9) Also often absent from the tale is any story of what happened in the aftermath of the searches. How many relatives were investigated? How did officials rule out wrongly identified persons, or attempt to confirm the identity of a perpetrator? Given that it failed in three separate cases, how tailored was the partial match search?

In contrast to Morrissey's unsuccessful first venture into familial searching stands the story of the apprehension of the alleged "Grim Sleeper" killer. After California adopted its familial search policy, investigators began using the technique. Ten attempts were unsuccessful, including one involving a genetic profile that linked the slayings of at least ten women in the Los Angeles area to one likely perpetrator, dubbed the "Grim Sleeper." (10) But in April of 2010, a second search in the case uncovered a potential match to a recently convicted offender believed to be the Sleeper's son. (11) After a sting operation in which officers surreptitiously collected a piece of pizza discarded by the suspect, tests revealed a match to the crime-scene samples and the suspect was arrested. (12) Unlike the Morrissey cases, the California search apparently not only proved successful in finding an actual relative, but also (likely as a result) produced a public record of the course of the follow-up investigation.

The Morrissey and Grim Sleeper case studies illustrate both the promise and the perils of familial DNA searching. On the one hand, familial searches offer the opportunity to solve horrific crimes that have frustrated all law enforcement efforts; on the other hand, they can generate false starts or cast suspicion on wholly innocent people solely on account of biological relatedness. This Article examines the practice, and ultimately argues against it on both utilitarian and deontological grounds. Part I provides a brief technical background. Part II argues normatively against the method, offering six separate arguments that reference both its practical utility and moral defensibility as a law enforcement tool. Part HI then addresses the legality, and in particular the constitutionality, of the practice. And finally, in the event that the previous Parts fall to persuade, Part IV suggests safeguards intended to minimize the intrusiveness and discriminatory potential of such searches.


    1. Forensic DNA: Mechanics

      A person's genome is made up of 3.2 billion nucleotides (abbreviated as G, T, C, or A) inherited equally from one's mother and father and stored in divided bunches on twenty-three paired chromosomes. (13) These chromosomes are found in the nuclei of each of the roughly 100 trillion cells that make up a human being. (14) Genome "sequencing," or the process of unpacking the genetic strand to uncover the letters and put them in order, has revealed that the vast majority of DNA--over 99.7 percent--is identical between two people. (15) However, certain stretches of the DNA strand, called "microsatellites," contain a finite quantity of variability that can serve to distinguish one individual from another. (16)

      The most common form of forensic DNA typing in the United States, known as "STR" or "single-tandem repeat" typing, looks to thirteen places (or "loci") on the genomic strand and counts the number of times certain known sequences repeat themselves. (17) These are referred to as the "autosomal" loci, because the genes are spread across the twenty-two chromosomes that are identical in both sexes, as contrasted to the "Y-STR" loci, which reference genetic material found only on the male Y sex chromosome. At each locus, analysts measure two repeat lengths, otherwise known as "alleles"--one descended from the mother and one from the father. By counting the repeats at thirteen loci, an analyst can obtain twenty-six discrete measurements that help individuate one person from another. (18)

      Because these twenty-six alleles are directly inherited from one's biological parents, there is a significant probability that two people who share biological ties will also share a large number of alleles in common. At minimum, a child and a parent will match at thirteen alleles, for instance. Due to the unpredictability of inheritance (since, of course, it is possible for one sibling to inherit one-half of a parent's twenty-six alleles while the other inherits the other half), it is not possible to state definitively how many alleles two siblings will share in common. (19) However, one estimate suggests that siblings on average share roughly 16.7 alleles in common. (20) Interestingly, the probability of overlap turns on several factors--most pertinently on common inheritance, but also on the likelihood that the parents themselves shared a particular allele and the commonness of that...

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