The police DNA database- crime fighting tool?

Next week sees the opening of the University of Leicester’s Alec Jeffreys Forensic Science Institute. In the first of two blog posts, Dr John Bond OBE shares his thoughts on the police DNA database.

In 1995 the government set up a national database to hold DNA samples from those convicted of certain offences. In parallel with this, DNA profiles from material recovered from crime scenes was also added to the database, the idea being that the police could then ‘match’ offenders to their crimes by the DNA left behind. The driving force for this was the growing success of DNA as a means of identifying offenders, pioneered here at the University of Leicester.  Government thinking was that capturing offenders’ DNA early on in their criminal careers would make identification of offenders easier if and when they moved on to more serious crime, such as violence, sexual offences etc. However, it soon became clear that the DNA database was much more useful at identifying offenders than originally anticipated and so the range of offences for which DNA was collected at both the crime scene and from offenders was increased.  However, the rate of growth of offenders on the database was not rapid enough for the government who, in 2001, amended the law to allow DNA samples to be retained from those charged (rather than convicted). But still the database did not grow quickly enough and so, in 2004, the law was changed again to allow DNA samples to be retained from those arrested, even if not subsequently charged with an offence. This change in legislation was coupled with a massive investment in DNA by the government under the ‘DNA Expansion Programme’ with over £300 million pumped into English and Welsh police forces to expand their use of DNA (including adding arrestee samples to the database).

This expansion was reported by the government as an overwhelming success with the number of crimes detected as a result of a DNA ‘match’ quadrupling during the expansion programme. Today, the legislation remains as enacted in 2004 with just about all arrestees (except in Scotland) being required to give a sample of their DNA for the database. This legislation has been challenged successfully in the European Court with a ruling that those not convicted of a criminal offence should not have their DNA retained on the database. To date, the government has not amended the legislation and why should it?

The success of the database in terms of detecting crimes that would, most likely, otherwise go undetected has been proven not only for serious crime (as originally envisaged) but also for ‘volume’ crime such as burglary and car crime.  Today, the DNA database is used daily by police forces across the United Kingdom to provide both the name of a suspect and the evidence with which to question them. Although receiving publicity for high profile offences or so-called ‘cold cases’ where DNA evidence has been used to identify an offender, it is detecting a countless number of every day volume crimes that has transformed the way in which the UK police service goes about investigating these crimes.  Just think about it, your car is broken into and the expensive Satnav stolen. With no witnesses, solving the crime relies more and more on forensic science and, for crimes like this, that means either DNA or fingerprint evidence.  Older methods of crime investigation in which a ‘local’ bobby would recognise the hand of a particular criminal at work and then go and knock on their door have long gone and, without technology to assist in solving the crime, the opportunities for detection are more limited.  But why should those who have not committed a crime be on the DNA database?  A good question, and an equally good question is – why is all this fuss just about DNA?  Legislation that amended the law to allow DNA retention from arrestees also applies to fingerprints but very little (if anything) is ever heard about peoples’ rights and the national fingerprint database. In many ways, fingerprint evidence is more powerful than DNA evidence in that fingerprint evidence is still regarded by many in the judicial system as conclusive (although this view is changing in the light of the Shirley McKie case in Scotland), whereas DNA evidence is always quoted with statistical odds and has an unfortunate ability to be innocently transferred between individuals or between surfaces (something referred to as ‘innocent contamination’). So why single out the DNA database.  Well, I suspect this is because there is public concern that the small part of the DNA molecule that is profiled for the DNA database might, in some way, be used for non-criminal purposes such as identifying a predisposition to illness.  But to single out DNA in this way and argue against retention, as was done in the European Court, shows a lack of understanding of what data the police hold and for what purpose it can (both legislatively and technologically) be used.

Why not extend the databases (both fingerprints and DNA) to all citizens, thereby removing these being seen as ‘criminal’ databases. Overnight, such an extension would clear up countless crimes as evidenced by the many hundreds of thousands of unidentified crime scene DNA profiles and fingerprints on the databases.  Of course, much of this crime scene evidence will belong not to the offender but to either the victim of someone else with legitimate access to the crime scene (maybe a friend or relative). However, many more of these crime scene DNA profiles and fingerprints will identify an offender who, to date, has evaded the attention of the police. The concern that such a ‘citizen’ database will convict the innocent is countered by our judicial system that requires evidence to be beyond reasonable doubt and, as already stated, requires other supporting evidence in addition to DNA evidence. After all, how often have you heard someone say that, in answer to this question, “If you are not a criminal, then you have nothing to fear”?

Dr John W Bond OBE, Senior Lecturer, Department of Chemistry, University of Leicester.

Now read Dr Lisa Smith’s view on the DNA Database.



  1. Chris Williams
    Posted 28/11/2012 at 20:05 | Permalink

    You are right, a DNA database is useless in tracking down the post thief.


  2. Chris Williams
    Posted 20/11/2012 at 22:15 | Permalink

    One reason Britain gave up the death penalty is the number of innocent people convicted by our judicial system. The inadedquacy of the judicial system is the reason it will never be brought back and is the main reason for public concern about the DNA database.


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