History of DNA database in general and in criminal investigations
A DNA database is simply “a computer database containing records of DNA profiles” (GeneWatch UK 3). While DNA databases are popularly known for documenting DNA profiles from crime scenes, they can also be made of DNA profiles of individuals.
While DNA profiling came into application for the first time in 1984 when a Ghanaian resident was identified as the biological son of a UK-residing woman in addition to three siblings (M’Charek 519), the first DNA database was established about a decade later. From a crime investigations perspective, the first DNA database in the world containing DNA profiles of individuals who were convicted of criminal offences was developed in 1995 in the UK (Linacre 1841). The first instance of use of a DNA profile as a crime scene evidence was done by the UK police back in 1985. In 1998, the first ever conviction based on DNA profile in the U.S. was conducted (Varsha 181). Since then, use of DNA profiles stored in DNA databases has become widely accepted for exoneration or implication purposes in both criminal and civil proceedings. Use of DNA evidence in the United States’ court system was approved by the National Research Council in 1992.
While the initial DNA database was based on convicted individuals, this has changed such that databases can contain profiles for persons who are not criminally implicated. The UK DNA database has even changed its name from The Criminal Justice DNA Database to National DNA Database (NDNAD). In addition, many other countries other than the UK and the U.S. have developed DNA databases containing DNA profiles for convicted persons only (Linacre 1841).
Technology of DNA analysis for criminal investigations
The understanding of exactly how DNA analysis is used for criminal investigations is very pertinent. DNA forensic scientists utilize variable regions in an individual’s DNA make up in order to come up with a DNA profile that is unique to that individual one. Biological evidence such as hair and body fluids is collected from a crime scene and after DNA extraction the presence of DNA markers is determined. First, DNA probes are developed the way they can bind in a complementary manner once they identify such a DNA sequence in the suspect’s sample. A DNA fingerprint is developed from the binding of the probe in the sample DNA. A match in the DNA profiles of the suspect’s sample with that of the sample collected from the crime scene indicates that the suspect was most likely involved in the crime scene (genomics.energy.gov para 4). By using more DNA probes in the analysis, the likelihood of getting the true match increases. It is identified that since the uniqueness of a marker is weak, it requires as many regions as possible matching with the crime scene DNA fingerprint.
After samples are collected from a crime scene, a laboratory analysis of the sample is conducted. This usually involves DNA extraction and amplification to come up with a DNA profile. Short and specific DNA sequences are generated through DNA restriction in order to come up with sequences that can bind with DNA probes. Some of the DNA technologies utilized for forensic purposes include RFLP, PCR analysis, STR analysis, and mitochondrial DNA analysis as well as the Y-chromosome analysis (Genomics.energy.gov para 6).
Explanation of DNA and it use in criminal investigations
DNA is a chemical that is present in all body cells. It forms a large proportion of the chromosomes’ constituents in every living organism. This implies that obtaining even a very small sample containing body cells is enough to reveal the genetic pattern of the individual. One unique characteristic of DNA that makes it come in handy in crime investigations is that DNA remains constant for every individual regardless of the age (Weekes para 1). Another important characteristic of DNA is that every individual (with identical twins exempted) has a unique genetic code thus individuals can be uniquely identified using their DNA code.
The above unique characteristics are harnessed in a crime investigation to connect a suspect to a crime. Only specific DNA sequences are utilized for this purpose. When people commit crimes, they usually leave behind traces of DNA in form of body fluids such as semen or their root hairs. Even a mere touch of an object is enough to leave cells which can be harnessed for DNA extraction and amplification. Other than samples collected from the crime scene, police also extract samples from suspects. After laboratory analysis of the sample and matching the profiles with the crime scene sample profile, conclusions are made on whether the individual was likely involved in the crime or not. The analysis entails looking for given DNA markers, whose presence is confirmed if the markers “bind to a complementary sequence in the sample DNA” (Varsha 182) forming a unique pattern. This unique pattern is matched against a profile of DNA collected from the crime scene to determine whether the suspect was most likely involved in the crime.
How databases are used in criminal investigations
After collecting DNA samples from crime scenes or suspects and subsequent processing to obtain DNA profiles, the profiles are then ready for matching in the DNA database. Other than using DNA profiles for matching with profiles contained in databases for identification purposes, DNA profiling has taken a new dimension as an investigative tool. In this case, it becomes possible to come up with a suspect in a scenario where there was none. This usually happens with national databases such as the NDNAD which contain profiles for convicted and non-convicted individuals. Trace DNA evidence is matched against profiles present in the database and in the event that a match is identified, it becomes possible to associate an individual with the crime.
DNA databases come in handy in looking for a crime suspect, as opposed to the idea of using DNA profile to get evidence regarding an already known suspect. This kind of search where a new profile is matched against existing profiles in the DNA database for possible suspect is known as “speculative searching” (Wallace 28). With development of DNA databases containing individuals’ profiles, new suspects can be introduced and be linked to past investigations or future investigations through “cold hits”. DNA databases are therefore useful in the justice system as tools for exonerating individuals, convicting suspects as well as introducing new suspects.
DNA profiles are stored in a database with additional information such as the name of the suspect and the place where the sample was collected among other variables. This personal data can be obtained from the database and linked to information contained in other databases, thus giving more weight to the evidence linking an individual to a certain crime (Williams and Johnson 547). It also goes without saying that if individuals’ DNA profiles are contained in a database, they are ultimately suspects for crimes that may occur in future.
GeneWatch UK. DNA databases and human rights. 2011. Web.
Genomics.energy.gov. DNA forensics. genomics.energy.gov. 2009. Web.
Linacre, Adrian. The UK National DNA Database. The Lancet 361; (2003): 1841-1842. Print.
M’Charek, Amade. “Silent witnesses, articulate collective: DNA evidence and the inference of visible traits.” Boiethics 22.9; (2008): 519-528. Print.
Varsha. “DNA fingerprinting in the criminal justice system: an overview.” DNA and Cell Biology 25.3; (2006): 181-188. Print.
Wallace, Helen. The UK National DNA Database: Balancing crime detection, human rights and privacy. EMBO Reports 7; (2006): S26 – S30. Print.
Weekes, Rob. DNA database for criminals. International debate education association. 2009. Web.
Williams, Robin and Johnson, Paul. “Inclusiveness, effectiveness and intrusiveness: issues in the developing uses of DNA profiling in support of criminal investigations.” Journal of Law, Medicine & Ethics 33.3; (2005): 545-558. Print.