Skip to main content

Genetics: Databases

Volume 475: debated on Monday 28 April 2008

To ask the Secretary of State for the Home Department (1) whether any checks on the Dutch disk containing DNA samples of criminals remain to be completed; (196812)

(2) how many matches have been found between the Dutch disk containing the DNA samples of suspected criminals and (a) the national DNA database and (b) other records or databases checked; how many people whose profiles have been matched have been convicted of a criminal offence since January 2007; and what those offences were.

As part of an initiative to exchange data between the UK and Holland, 2,159 DNA profiles from crime scenes in Holland were searched against the UK National DNA Database. The operational police response to the DNA crime scene data supplied by the Dutch is being led by a group chaired by the Association of Chief Police Officers (ACPO) on which the Serious Organised Crime Agency, the National Policing Improvement Agency, the National DNA Database (NDNAD) Custodian, the Crown Prosecution Service and the Home Office are represented.

This remains a continuing police operation in liaison with the Dutch authorities.

I am continuing to liaise with ACPO to be clear when a formal report to Parliament would be appropriate.

To ask the Secretary of State for the Home Department (1) what estimate she has made of the number of adventitious matches expected to arise between crime scene DNA profiles submitted by law enforcement agencies elsewhere in the European Union and individuals' DNA profiles held on the national DNA databases in each of the next five years; (197981)

(2) what estimate she has made of the number of adventitious matches expected to arise between crime scene DNA profiles submitted by UK police and individuals' DNA profiles held on the national DNA database in each of the next five years.

[holding answer 31 March 2008]: When the UK National DNA Database (NDNAD) was set up in 1995, the SGM profiling system was used. This looked at six areas of DNA, plus a gender marker. The probability of an adventitious (chance) match between full SGM DNA profiles of unrelated individuals is of the order of one in 50 million. As the NDNAD grew in size, instances did come to light where different individuals were found to have the same SGM profile, hence the decision to change to SGM Plus in 1999.

The quoted probability of a match between full SGM Plus DNA profiles of unrelated individuals is one in one billion (i.e. one in a thousand million).

The NDNAD Custodian carefully monitors replicate DMA profiles loaded to the Database, and a key reason for doing this is to identify potential adventitious matches between SGM Plus DMA profiles derived from unrelated individuals. To date, no such adventitious match has been found. This indicates the SGM Plus match probability to be significantly lower than the figure quoted—it is probably better than one in one trillion (i.e. one in a million million).

Safeguards against possible miscarriages of justice arising from adventitious matches operate at two levels—firstly, further investigation of matches using the SGM Plus technique, and secondly, the fact that if a person is to be charged on the basis of a DNA match, the CPS require that there must be supporting non-DNA evidence available to be used in evidence. DNA evidence is one piece of the information that the courts would require for a successful prosecution.

Other EU states use different profiling systems and do not publish information on the likelihood of adventitious matches using these systems. However, the level of overlap between SGM Plus DNA profiles and those developed by other systems is that the discriminating power will typically be of the same order as the SGM (rather than the SGM Plus) level. It is thus extremely important that all possible opportunities are taken to improve the discriminating power associated with a match, for example by re-analysis of the sample to upgrade, the profile before any other information on the identity of a suspect nominated by a DNA match is disclosed to an overseas police authority.