Law Enforcement use of Genealogical (DNA) Databases (Part 3).

      It is important to realise that genealogical DNA databases are viewed and used by law enforcement investigators in exactly the same way as other sources or databases that are non-genealogical related. That is, they are used to establish a pool of ‘persons-of-interest,’ and then through old-fashioned detective work, that pool is narrowed down to a few possible suspects that will undergo a more thorough and rigorous check, hopefully narrowing that pool down further to a prime suspect.[1]

     The issue confronting the genealogist using the genealogical DNA databases for genealogical purposes becomes how law enforcement investigators use the DNA sample submitted by that genealogist, where the sole purpose of submitting the DNA sample by the genealogist was for personal genealogical reasons. As shown in an example in the previous Post (Part 2) though, law enforcement investigators will search credit card databases of companies to establish who may have purchased specific goods that may be in-common-with item/s that may have been seized at a crime scene. The purpose of the credit card database used by a company may have been established for the explicit purpose of monitoring income-expenditure, but an unintended use of that database has been to assist law enforcement investigators in investigating a major crime in creating a pool of suspects.[2] This is exactly the same situation that arises with the use of genealogical DNA databases being used by law enforcement investigators. (The way in which a law enforcement investigator actually uses a genealogical DNA database to develop a pool of suspects, and then narrow that pool down is addressed in the previous post (Part 2)). The only difference being, that in most cases, law enforcement investigators will require a Warrant issued by a Court for the production of information from a database, such as a credit card database, while accessing information in a genealogical DNA database, at this point in time, does not require a Warrant issued by the Court.

     The way in which evidence is collected by an investigator in relation to a criminal investigation will determine the usefulness of that evidence when the matter proceeds to Court. As the burden of proof is on the prosecution, the prosecution needs to establish beyond a reasonable doubt that the evidence it produces was collected in such a way that that its integrity cannot be questioned. Swanson et. al. argues that an investigator, in Court, must be able to

• Identify each piece of evidence that was collected at the crime scene and elsewhere, even if it is many years after it was collected,
• Describe, and show (through photographs, video etc), the location of each piece of evidence, and the condition of the evidence at the time it was collected,
• Assist in establishing a ‘continuity’ of the evidence – that is, show that from the time of collection, until presentation of the evidence in Court, the evidence was continuously in proper custody, and,
• Describe any changes that may have occurred in the evidence, between the time of the collection of the evidence, and its subsequent production as evidence in Court.[3]  

     With reference to the ‘continuity’ of a piece of evidence, Swanson et. al. states,

“Administratively, the chain of custody is the witnessed, written record of all individuals who have maintained unbroken control over the evidence since its acquisition by a police agency. It begins when an item of evidence is collected and is maintained until final disposition of that item. Each individual in the chain of custody has personal responsibility for an item evidence, including its care and safekeeping”.[4]

     It is for this reason that the actual DNA samples that genealogists submit to genealogical DNA testing companies cannot directly be presented as evidence in Court and used as direct evidence to contribute to the establishing of guilt against a suspect. There are too many uncontrolled factors present in the taking of the genealogical DNA sample, and the comparing of the sample against other samples in the genealogical DNA databases, so much so, that a rigorous chain of custody would be all but impossible to establish. For DNA evidence to be accepted as evidence in Court, the DNA evidence that was obtained from a crime scene needs to have been collected in a controlled way and accounted for through a ‘chain of custody’, and then compared to a DNA sample taken from a suspect, which was similarly taken in a controlled way, and again accounted for through a ‘chain of custody’, with the comparison of the two samples being undertaken in a law enforcement DNA database.[5]   

     One final issue to consider when looking at Genealogical DNA databases -v- Law Enforcement DNA databases, and why Courts specifically request that any results of a DNA comparison be structured with reference to the law enforcement DNA database, concerns the purposes behind the DNA databases themselves. Both databases have different algorithms for achieving the desired aim the database was created for. Genealogical DNA testing companies were created to identify a relationship between DNA samples submitted by genealogists, family historians, or those who may have an interest in what a DNA test may show. Bettinger indicates that genealogical DNA testing companies compare DNA samples and as a result of that comparison will make a relationship prediction based on the amount of DNA that is shared between the person submitting the sample, and a DNA ‘match’ within that database.[6] Law enforcement DNA databases on the other hand, are concerned with the degree of difference between a sample match and the rest of the population. The law enforcement DNA database is all about estimating a random match probability between the DNA sample that was submitted as part of an investigation, against the rest of the population as represented by a certain number of ‘control’ DNA profiles.[7] Law enforcement DNA database analyses seek to adduce  evidence that provides the probability that the sample of DNA obtained at a crime scene and the sample obtained from a suspect is so ‘different’ from the rest of the population that it could not possibly be any other person.

     This Post and the previous two Posts have laid out the theoretical basis behind the use of genealogical DNA Databases by law enforcement investigators. These Posts do not seek to provide support, or otherwise, of the use of genealogical DNA databases for anything other than genealogical purposes, but simply aims to provide a context with reference to the methods used in law enforcement investigation in identifying suspects in major crime, and how genealogical DNA databases can be used to achieve that. There are a number of ethical issues that arise as a consequence of law enforcement investigators using genealogical DNA databases for criminal investigation purposes, but those issues have not been dealt with here.  

Endnotes:

[1]     Richard H. Walton, Cold Case Homicides: Practical Investigative Techniques, Boca Ratan, CRC Press, 2006, p. 552-553.

[2]     Ibid.

[3]     Charles R. Swanson, Neil C. Chamelin and Leonard Territo, Criminal Investigation, 7^th edn, United States of America, McGraw-Hill, 2000, p. 52.

[4]     Ibid.

[5]     Crimes (Forensic Procedures) Act 2000 (NSW), s. 93.

[6]     Blaine T. Bettinger, The Family Tree Guide to DNA Testing and Genetic Genealogy, Cincinnati, Family Tree Books, 2016, p. 31.

[7]     John M. Butler, Fundamentals of Forensic DNA Typing, Burlington, Academic Press, 2010, p. 262.