DNA Technology and Police Investigations Research Paper

History

The comparison of biological material recovered from scenes of crime with that taken from known individuals has a long pedigree in forensic science; the practice has been used widely to assist investigations and support the prosecution of offenders. Several different technologies, each seeking to capture varying degrees of distinctiveness exhibited by particular biological attributes, have been used to make these comparisons. Historically, the most widely accepted of these has been serological analysis in which blood samples are assigned to one of a small number of “ABO” blood types in order to include or exclude individuals as the possible sources of such material. However, in 1985, Alec Jeffreys and colleagues at the University of Leicester published two papers which demonstrated a new method for capturing individual differences at the genetic level (Jeffreys et al. 1985a, b). Described as “providing a level of individual specificity that was light-years beyond anything that had been seen before” (Newton 2004), the potential forensic science implications of what was first called “DNA fingerprinting” were quickly realized by Jeffreys and others.

The first, and highly prominent, deployment of this new technology in criminal investigations occurred only 2 years after Jeffreys’ initial – and largely adventitious – laboratory discovery. Dawn Ashworth, a 15-year-old girl, went missing from her home in Northamptonshire on 31 July 1986. Her body was discovered 2 days later, and blood typing of semen recovered from her revealed identical features with semen obtained from the body of Lynda Mann who had been raped and murdered by an unidentified individual 3 years earlier (in both cases the semen donor was a Blood Group A secretor). The prime suspect for the murder of Dawn Ashworth was 17-year-old Richard Buckland, and following his arrest on 5 August 1986, he confessed to Ashworth’s murder. However, Buckland was not Blood Group A and could not be linked to the semen recovered from Ashworth’s body. In addition, he denied involvement in Mann’s death. Faced with the contradiction between the biological evidence and Buckland’s confession, investigators requested Jeffreys to extract DNA from both recovered semen stains and to compare them to a blood sample taken from Buckland. Jeffreys’ analysis concluded that Buckland’s sample did not match the crime scene semen, but the semen taken from both crime scenes matched each other. Following Buckland’s exoneration, the first ever mass DNA screening eventually resulted in the identification of Colin Pitchfork as the source of the semen, and Pitchfork was convicted of the two murders on 22 January 1988.

Despite this and other investigative successes in the UK and the USA, several technical limitations to this early form of forensic genetic analysis meant that it could be used only in a relatively small number of criminal investigations. These limitations included: the need to obtain relatively large quantities of DNA to undertake analysis; the time taken to complete the analytical process (several days or, in some cases, weeks); its unsuitability for use with degraded samples; the limited number of genetic markers that could be analyzed simultaneously; and the small number of samples that could be processed at one time. In addition, the criminal justice reception of forensic DNA fingerprinting was marked by an initial period of legal skepticism and methodological difficulty, especially concerning the estimation of “random match probability” and the communication of DNA profiling results by expert witnesses. The history of these “DNA Wars,” especially the way in which they were conducted in several high-profile US criminal prosecutions, has been well documented by legal and human science scholars (see, for example, Kaye 2010; Lynch et al. 2008; Lynch and Jasanoff 1998).

Following these early controversies, and the stabilization of confidence in DNA profiling that resulted from their resolution, a series of subsequent changes in the methods for producing profiles also gradually overcame the technical shortcomings described above. The development of polymerase chain reaction (PCR), first reported by Kary Mullis in 1985/6, and its subsequent automation played a central role in this development by enabling the profiling of small and even degraded DNA samples through amplification. In the early 1990s, the shift to short tandem repeat (STR) multiplexes also meant that genetic information garnered through PCR became more easily comparable and digitizable, which made possible the automated computerized comparison of data-based profiles.

DNA Evidence Recovery

In most jurisdictions, only trained crime scene examiners and forensic scientists recover biological material at scenes of crime. Some, however, also permit police officers to do so, at least in cases other than those of the most serious crimes. Regardless of these differences, investigators are increasingly conscious that aspects of the collection, packaging, recording, transporting, and laboratory handling of forensic genetic material can be subject to challenge in the course of judicial hearings, so all these practices are subject to strict protocols. What might otherwise be compelling DNA evidence can become “valueless if the authenticity of the samples used in the investigation cannot be confirmed” (Lincoln 1997). This means that very high levels of care are required to avoid prejudicing the weight otherwise given to the presence of DNA evidence recovered from crime scenes by lapses in continuity or by the use of inappropriate collection or preservations methods.

One clear feature of the trajectory of DNA profiling since the late 1980s has been the increasing success of forensic laboratories at being able to obtain analyzable quantities and qualities of DNA from an increasing variety of sources, including “trace” or “touch” DNA. In the early 1990s, Wiegand and associates were able to derive and profile DNA from debris obtained from fingernail scrapings and later from epithelial cells left on a victim’s body following strangulation as well as cells left on strangulation tools. DNA analysis using an increased number of amplification cycles has been used successfully in UK forensic science casework since 1999 and a large number of studies have reported on the actual and potential uses of such “low copy number” (LCN) or low template (LT-DNA) analysis. While this technique has made possible the production of profiles from very small and also degraded samples of DNA, these profiles are subject to a series of technical effects which can make their interpretation very difficult. There has also been one significant UK judicial ruling that questioned the robustness of this particular practice (Weir, J. [2007] “The Queen v Sean Hoey,” The Crown Court Sitting in Northern Ireland). For these reasons, and despite recent work conducted on behalf of the UK Forensic Regulator, the use of LT-DNA remains contested in many jurisdictions.

DNA Databasing

Throughout the late 1980s and into the early 1990s, all applications of forensic DNA profiling technology to criminal casework required the temporary storage of DNA profiles from nominated suspects, or other persons of interest, so that each individual’s profile could be compared with those obtained from crime scene samples. The limited accounts of these practices suggest that such profiles (and usually the physical samples from which they were derived) were held for varying periods of time in local police or forensic laboratory collections. These collections were not usually regulated by formal mechanisms or by external bodies, but their existence caused little unease, perhaps because the practice was not widely known outside of restricted police and forensic science circles. However, it was not long before the use of DNA profiling expanded beyond reactive forensic casework in some jurisdictions. Forensic scientists in the UK, the USA, Austria, and New Zealand argued that searching DNA profiles recovered from crime scenes against profiles held in larger and centralized databases could, by the provision of “cold hits,” facilitate the early identification of many more potential suspects (as well as the exclusion of some others as persons of interest). Once further technological advances made it possible to construct easily transportable digital representations of profiles and store them in continuously searchable computerized databases, the stage was set for a vastly expanded role for DNA profiling in many criminal investigations. In turn, this meant that the limitations of existing and varied local collections required them to be replaced by more extensive forensic DNA databases capable of contributing to the successful detection and prosecution of more offenders – at least in jurisdictions where there was the political will and administrative resolve to support such innovations (descriptions of the early days of DNA databasing in these and other jurisdictions can be found in Hindmarsh and Prainsack 2010).

The last 20 years have witnessed an increasing number of criminal jurisdictions in which such forensic DNA databases have been established – usually, but not always, at a national level. The first national forensic DNA database was created in England & Wales in 1995. Three years later, it was followed by the official launch of the US Federal Bureau of Investigation’s Combined DNA Index System (CODIS), although all 50 US state databases were not fully connected through CODIS until 2004. Many other nation states established their own national forensic DNA databases during the last decade of the twentieth century, and each year sees the addition of more states authorizing or creating such collections. These hybrid scientific-legal innovations have usually required legislative changes and the provision of additional funds to create and populate such databases with profiles obtained from known subjects and those obtained from biological material recovered from crime scenes. Particular commercial actors – largely but not exclusively biotech companies – have also been prominent advocates and supporters of these state-driven criminal justice ambitions, and their interests have complemented the enthusiasm of many prominent policing stakeholders.

There is also widespread public support for the use of forensic DNA profiling in most contemporary democratic societies. Allowing for some simplification, the global trajectory of forensic DNA database expansion has followed a distinctive shape in which the types of people from whom DNA samples can be taken without consent, profiled, and retained have become greater. This has most often begun by sampling only those involved in the most serious crimes against the person, then moving on to include those involved (or suspected of being involved) in a range of property crimes. Police have also been authorized to take DNA samples at earlier points in investigative and judicial inquiries (for example, at the point of arrest rather than the point of charge, or even conviction). The period during which DNA profiles and samples can be retained has often been extended, and more DNA has been recovered from crime scenes. In addition to these developments, which together have resulted in the existence of much larger databases, the investigative applications of databased profiles have also expanded; there are increasing efforts to make possible the sharing of DNA profile information between criminal jurisdictions, for example, within the European Union via the Prum Treaty, and beyond the EU through INTERPOL.

Current Databasing Practice

Taking DNA from suspects, and using these and crime scene DNA profiles as intelligence to support criminal investigations and as evidence to support prosecutions, are now central aspects of policing in a large number of countries. In those jurisdictions that have established a “national” DNA database, the vast majority of profiles entered are obtained from suspects during the investigation of crime. For those eager to promote and extend the powers of the police to sample criminal suspects, emphasis is placed on the immediacy of DNA profiling to exonerate individuals from, as well as implicate individuals in, further criminal investigations. The point is often made that enabling the police to obtain DNA samples from suspects introduces a reliable and objective method of evaluating their presence at a scene of crime. Yet, in order to obtain such a sample, the suspect must undergo a procedure to extract bodily material, and beliefs about the significance of this bodily intrusion color legislative decisions about forensic DNA sampling. Most states have enacted legislation that carefully specifies the situations in which the police may legally “interfere” with bodily integrity. Affording the police the authority to take DNA samples without consent involves making a number of legislative decisions. The first involves deciding at what stage in criminal procedure an individual should be subject to compulsory DNA sampling. A second, and related, issue is whether the police themselves should possess the authority to administer the collection, or if they should be required to obtain judicial approval. A third decision pertains to the types of offenses that should allow the compulsory sampling of suspects. And, following that, a fourth issue is whether such sampling should be relevant to the specific offense in question. A subsequent question arising is that of DNA retention: from whom, for how long, in what form (biological sample and/or digitized profile), and in what ways may the retained DNA material be used in the future.

Some states have reduced the significance of these issues and thus maximized the possible sampling of suspects. Equally, other states have minimized sampling because they have assigned more significance to them. The obvious example in the former category is the UK (England & Wales) which permits compulsory DNA sampling at the earliest point of investigation (upon arrest of a suspect) by the police for any “recordable” offense regardless of whether such a sample is relevant to the investigation. An example of a country in the latter category is France where nonconsensual sampling of suspects is completely prohibited.

In some states of the European Union (for example, The Netherlands, Luxembourg, and Malta), police are able to take compulsory DNA samples from individual suspects but such sampling requires judicial authority. Requiring the police to obtain this authority is a significant element in the distribution of powers across the criminal justice system. It prohibits the automatic sampling of criminal suspects by the police and transfers authority elsewhere, requiring the police to make a strong argument for compromising a person’s bodily integrity. Nevertheless, it is increasingly common in many jurisdictions for the police to take DNA during the investigation of certain types of offenses. Most often, these are serious offenses which involve violence against persons. And some countries possess legislation which limits the collection of DNA from suspects in relation to specific – usually more serious – offenses. The situation in the USA is made more complex by differences between the states of the Union, but there seems a general trend there to establish “arrestee databases” in which DNA is taken, stored, and speculatively searched on arrest, even if subsequently removed (or at least sequestered) when individuals are not prosecuted, or if prosecutions do not result in findings of guilt. The many and constant changes in legislative frameworks governing forensic DNA databasing across the world are monitored by several police and civil society groups; from time to time, publications by INTERPOL and by a consortium of UK and US civil society groups provide serially updated accounts of these developments (see www.interpol.int and http://dnapolicyinitiative. org/).

Key Issues And Controversies: Claims-making And The Measurement Of Utility

Criminal justice researchers in the UK were among the first attempting to establish the value of DNA profiling and databasing to criminal investigations other than by citing conspicuous case successes. A series of studies, all funded by the Home Office, reported mixed success in this regard, although some UK government publications confidently asserted significant gains in the proportion of crimes detected when DNA evidence was available to investigators (McCartney 2006a, b). More recent studies have been carried out in the USA, mostly funded by the National Institute of Justice. Two of these have been especially ambitious. Roman and colleagues (Roman et al. 2008) carried out the first randomized control trial of the use of forensic DNA profiling across several US police districts in which the results of burglary investigations during which DNA evidence was collected but not analyzed were compared with those in which such evidence was made available to investigators. A second major study, of the role of forensic science in securing prosecutions, but also providing separate data specifically on DNA profiling, has recently been completed by Peterson and others (Peterson et al. 2010). This work followed the investigative process in a number of different kinds of crime (including homicide, rape, aggravated assault, robbery, and burglary) through the criminal justice system in order to assess the contribution of forensic science to the outcome of investigations and prosecutions. While a range of forensic evidence types was considered, particular attention was given to DNA analysis because of its ability to provide individualizing evidence capable of associating particular suspects to crime scenes. Despite these and other studies, there remains disagreement over the extent to which research has yet provided a robust account of the utility of DNA profiling and databasing to criminal investigations. The UK Human Genetics Commission, along with academic researchers in many jurisdictions, has commented on the need for better data to be provided by the custodians responsible for the operation of national DNA databases as well as by the police who are responsible for the use of DNA match information in support of individual investigations (Human Genetics Commission 2009).

Key Issues And Controversies: DNA Databases And Human Rights

All sampling and databasing of the genetic profiles of individual suspects by the police – especially those taken without consent – involves consideration of a number of legal, social, and ethical issues. As reflected in the comment of the Council of Europe Committee of Ministers from 10 February 1992, such sampling must “[t]ake full account of and not contravene such fundamental principles as the inherent dignity of the individual and the respect for the human body, the rights of the defence and the principle of proportionality in the carrying out of criminal justice.” For some critics, forensic DNA sampling and databasing threaten the bodily integrity of citizens who are subject to the forced and nonconsensual sampling of their genetic material based on decisions of police and judicial actors prior to findings of guilt by relevant authorities. In addition, there is concern that DNA databasing also violates privacy rights by allowing the use of profiles and the storage of biological samples, storage which itself creates the potential for the future misuse of such samples held in state and privately owned laboratories.

Accordingly, these and other legal, social, and ethical issues have been explored in several academic and policy studies. In the UK, two major agencies – the Nuffield Council on Bioethics (2007) and the Human Genetics Commission (2001, 2002, 2009) – have both published substantial critical reports on the distinctively forceful legislative and operational developments in DNA databasing that occurred in England & Wales between the establishment of the National DNA Database in 1995 and the decision of the Council of Europe’s European Court of Human Rights in the case of S & Marper v the UK Government in 2008.

In addition, the monitoring group Genewatch UK have also been actively interrogating official statements and statistics on the National DNA Database for a number of years as well as appearing before several House of Commons Select Committees that have inquired into aspects of forensic DNA profiling and databasing in England & Wales (see http:www.genewatch.org/). In the USA, the American Civil Liberties Union has frequently criticized the state and federal expansion of DNA collection and retention, and the American Society of Law, Medicine and Ethics sponsored a series of national workshops and conferences on US developments in DNA profiling, attended by many of the major academic, scientific, and operational experts in the field between 2003 and 2006.

Key Issues And Controversies: Recent Innovations In Forensic DNA Analysis

There are many investigations in which genetic material has been recovered from a crime scene but no matches with databased profiles have been made. In such circumstances, investigators may seek other ways to infer personal features of an unknown individual from the DNA that they have left at the scene. New forms of genetic knowledge, technological improvements in sample processing, and the premium on the investigative ingenuity necessary for the detection of “hard-to-solve” serious crime contribute the means and desirability for constant innovations in methods for interrogating the informational content of biological samples obtained from scenes of crime. At present, analysis can be undertaken to gain information about phenotypical attributes, “biogeographic ancestry,” and “familial relationships.” Some interrogations involve the direct examination of coding regions of the human genome – genes themselves – while others rely on new ways of using information from the noncoding areas already examined by conventional forensic profiling. The most significant of these approaches are briefly described in the following sections.

“Genetic Ancestry,” “Population Groups,” and Forensic Investigations. One particularly complex area of genetic information of interest to criminal investigators has been that of patterned human genetic diversity. Knowledge of the differential variability of genotypes according to population groups has informed the calculation of random match probabilities since the early days of DNA profiling. While population genetics are largely of interest to the specialized forensic community, the ability to infer the “biogeographic” origin of an individual who left otherwise unidentified biological material at a crime scene may be of significant interest to investigators. Reliable inferences of the “racial origins,” “ethnic origin,” “ethnic affiliation,” or even “ethnic appearance” of such an individual can be used to focus subsequent inquiries, to determine an interview strategy, to compare with witness statements, or to design an intelligence-led mass DNA screen. However, there are significant conceptual and operational uncertainties surrounding such categorizations of individuals. Moreover, there is a danger, well articulated, for example, by Duster and colleagues, that “race” will be reified in the attempt to define distinctive human population groups and subgroups. These critics also point to the ways in which questions of genetic “ancestral attribution” for these limited and pragmatic purposes can easily become confused with more ambitious theoretical assertions concerning the biology of “race” as well as “some old and dangerously regressive ideas about how to explain criminal conduct” (Duster 2003: 151).

Despite these problems, a number of forensic laboratories and agencies have added to their analysis of autosomal DNA STRs and SNPs, Y-chromosome STR and Y-chromosome SNP multiplexes for the analysis of loci whose polymorphic range is already databased by a variety of international consortia. The Y-chromosome is an especially suitable site for such investigations because of the low rate of recombination on this chromosome. This means that particular malespecific haplotypes are preserved across generations and vary systematically across different population groups. The research and reference databases used to inform developments of this kind are the Y-STR haplotype reference database, the US population database, and a European population database (see www.yhrd.org).

Autosomal Single Nucleotide Polymorphisms (SNPs). There have been several surveys of such polymorphisms, many of which are collected together in a global haplotype collection known as the “HapMap” (www.hapmap.org). SNPs have a much more limited polymorphic range than STRs, so that about four times as many SNPs are needed to produce profiles capable of discriminating individuality as those used by STR typing. Nevertheless, the establishment and expansion of SNP forensic databases alongside current STR collections is not out of the question, and the analytical scope of SNPs means that they can serve valuable forensic identification functions, especially in situations where samples are too degraded to make STR typing possible. The Y Chromosome Consortium has provided a “phylogenetic tree” which describes the history of 18 major lineages of diverse SNP haplotypes across human population, and other scholars recently discussed the development and use of Y-SNP multiplexes to support inferences of population origin.

It is difficult to determine the significance of these efforts to provide information about genetic ancestry. A clear preference for SNP markers over STRs seems to have emerged over the last few years, and large numbers of SNPs are now combined to form “ancestry informative markers,” some of which have been used in forensic casework. However, until recently, there have been problems in standardizing such markers and in the standardization of haplotype nomenclature. Furthermore, the increase in populations of mixed origin is a feature of complex urban societies so that “indirect deductions about individuals are often unreliable” (Jobling 2001: 161). Even when the pattern of differential SNP distributions is used to “improve” the accuracy of such inferences, as in the case with “proportional ancestry” studies, significant uncertainties remain.

Inferring Specific Phenotypical Features. In addition to efforts at identifying the genetic ancestry of unmatched crime scene stains, forensic scientists and police investigators remain interested in whether interrogations of such stains may yield information about a wide repertoire of visible characteristics of their donors. For the purposes of police investigations, the ability directly to determine individuals’ physical characteristics may be more appealing than inferring those characteristics from assumptions of biogeographic ancestry. The most frequently used method of direct interrogation – of the amelogenin locus – determines the biological sex of the DNA source and is already incorporated into the majority of multiplex systems. Aside from this test, however, the research literature reveals limited success in attributing phenotype from genotype in ways that are practically useful to investigators.

An initial review of forensic work in this field suggests that positive results remain scarce, and are focused on probabilistic inferences about pigmentation (see for example Kayser and de Knijff 2011). While analysis of the human melanocortin-1 receptor gene can be used to indicate “red hair” in the relevant subject, hair loss and hair coloring can make this test problematic when applied in investigative contexts. Both STR and SNP profiling are of interest to forensic scientists keen to develop predictive tests for a range of other observable physical characteristics including eye color, skin type, and height. It seems likely that SNP analysis may prove more successful than STR markers as the basis for such tests. This is not simply because most genomic mutations are single base changes but also because there is considerable research being carried out beyond the forensic community to identify SNP polymorphisms and their effects on a variety of human attributes.

Familial Searching. The term “familial searching,” as used by forensic scientists and police officers, refers to a form of database searching reliant on knowledge about the probability of matches between the STR markers of two members of the same family (as opposed to the probability of matches between these markers when the individuals compared are unrelated). This practice makes use of understandings of inheritance that prefigured the discovery of the structure of DNA and which had been largely applied to understanding variation in human, animal, and plant phenotypical characteristics (for a summary account of these assumptions as applied to the forensic context, see Bieber et al. 2006). Because familial searching relies on identifying a pool of possible genetic relatives of a suspect, who are then subject to more direct investigation (typically by being interviewed by the police), forensic science policy makers in the UK and elsewhere have also acknowledged that a number of ethical issues need to be addressed when this strategy is being considered (see Greeley et al. 2006; Haimes 2006). Issues arise in both the searching of profiles on a database and in the subsequent investigative trajectories that follow the provision of a list of individuals derived from such a search. A genetic link between individuals might be previously unknown by one or both parties and police investigations may make such information known to them for the first time. Equally an investigation may reveal – to investigators, if not to informants – the absence of genetic links which participants assumed to have existed. There is also the question of whether this kind of use of an individual’s databased DNA violates promises of privacy and confidentiality made when genetic material was originally donated voluntarily, for example, in the course of a mass DNA screen. Furthermore, assertions about criminality, geography, and familial relatedness that are central to the use of this forensic methodology are especially problematic – even if they do accord with the rhetorical endoxa of many detectives – and they reveal pervasive problems associated with the confusion between “genetic” and “social” relatedness (“families” are not only constituted through genetic lines but through clusters of non-genetically related individuals) as well as the implicit assumption that criminality is fostered because of such relatedness (either for genetic or social reasons).

Conclusion

This research paper has outlined the history of the main DNA technologies that are currently used in police investigations along with their reception by criminal justice actors, especially in the UK and the USA. The uncertainties reflected in the “DNA Wars” of the 1980s and 1990s have diminished as scientific and legal agreements about the strength and limitations of many of these technologies have stabilized. Police enthusiasm for DNA technology has grown, and in many jurisdictions, legislators have increased police powers in order to maximize its potential uses to support criminal investigations and prosecutions. A variety of international bodies (especially the European Network of Forensic Science Institutes, The American Society of Crime Laboratory Directors, and the International Society for Forensic Genetics) support efforts to standardize forensic genetic practice and shape the education of relevant scientific and legal personnel. At the same time, new normative and empirical uncertainties arise as legislative, operational, and technical innovations are critically appraised by scientific, legal, and human science scholars. Questions of scientific adequacy, investigative utility, and ethical acceptability, as well as the relationship between each of these questions, are sure to engage criminological interest for the foreseeable future.

Bibliography:

1. Aronson JD (2007) Genetic witness: science, law and controversy in the making of DNA profiling. Rutgers University Press, New Brunswick
2. Bieber FR, Brenner C, Lazer D (2006) Finding criminals through DNA of their relatives. Science 312:1315–1316
3. Duster T (2003) Backdoor to eugenics, 2nd edn. Routledge, New York
4. Fraser J, Williams R (2009) Handbook of forensic science. Willan, Cullompton
5. Gerlach N (2004) The genetic imaginary: DNA in the Canadian criminal justice system. University of Toronto Press, Toronto
6. Greeley HT, Riordan DP, Garrison NA, Mountain JL (2006) Family ties: the use of DNA offender databases to catch offenders. J Law Med Ethics 34:248–262
7. Haimes E (2006) Social and ethical issues in the use of familial searching in forensic investigations: insights from family and kinship studies. J Law Med Ethics 34(2):263–276
8. Hindmarsh R, Prainsack B (2010) Genetic suspects: global governance of forensic DNA profiling and databasing. Cambridge University Press, Cambridge
9. Human Genetics Commission (2001) Whose hands on your genes? A discussion document on the storage protection and use of genetic information. HGC, London
10. Human Genetics Commission (2002) Inside information: balancing interests in the use of personal genetic data. Department of Health, London
11. Human Genetics Commission (2009) Nothing to hide, Nothing to fear? Balancing individual rights and the public interest in the governance and use of the national DNA database. HGC, London
12. Jeffreys AJ, Wilson V, Thein SL (1985a) Individualspecific ‘fingerprints’ of human DNA. Nature 316: 76–79
13. Jeffreys A, Wilson V, Thein SL (1985b) Hypervariable ‘minisatellite’ regions in human DNA. Nature 314: 67–73
14. Jobling MA (2001) Y-chromosomal SNP haplotype diversity in forensic analysis. Forensic Sci Int 118:158–162
15. Kaye DH (2010) The double helix and the law of evidence. Harvard University Press, Cambridge, MA
16. Kayser M, de Knijff P (2011) Improving human forensics through advances in genetics, genomics and molecular biology. Nat Rev Genet 12(3):179–192
17. Lincoln PJ (1997) Criticisms and concerns regarding DNA profiling. Forensic Sci Int 1997:23–31
18. Lynch M, Jasanoff S (1998) Contested identities: science, law and forensic practice. Soc Stud Sci 28(5–6):675–686
19. Lynch M, Cole S, McNally R, Jordan K (2008) Truth machine: the contentious history of DNA fingerprinting. Chicago University Press, Chicago
20. McCartney C (2006a) The DNA expansion programme and criminal investigation. Brit J Criminol 46:175–192
21. McCartney C (2006b) Forensic identification and criminal justice: forensic science, justice and risk. Willan, Cullompton
22. Nuffield Council on Bioethics (2007) The forensic uses of bioinformation: ethical issues. The Nuffield Council, London
23. Peterson J, Sommers I, Baskin D, Johnson D (2010) The role and impact of forensic evidence in the criminal justice process. National Institute of Justice, Washington, DC
24. Roman JK, Reid S, Reid J, Chalfin A, Adams W, Knight C (2008) The DNA field experiment: cost-effectiveness analysis of the use of DNA in the investigation of high-volume crimes. Urban Institute, Washington, DC
25. Williams R, Johnson P (2008) Genetic policing: the use of DNA in criminal investigations. Willan, Cullompton