The future of DNA profiling – how will it affect your cases?
By Duncan Woods on 21/05/15Share:
You may be unaware that a major increase in the sensitivity of DNA profiling techniques used in the UK is being introduced. At a scientific level, this marks the latest improvement in profiling technology, but when it comes to assessing the evidential value of the results, much of the knowledge accumulated over many years’ use of the old technology will become less certain.
On one level, the new methods will obtain detailed profiles from the type of samples that previously would have failed or produced results that could not be said to be significant. Samples that previously gave low level, uninterpretable results may now give interpretable results. The improvements are such that we are sure many old, cold, unsolved cases are likely to be revisited. Old stored samples and exhibits will be recovered and analysed to see whether valuable results can now be obtained.
To complicate matters, the current forensic service providers are each opting for one or more of the new analytical systems, so there will no longer be one universal system for the UK. Also being introduced are a number of highly sophisticated statistical methods for drawing out significance from complex DNA profiles which previously would have been given little or no evidential value. In other words, from the sort of multi-person, mixed DNA profiles that a frequency figure could not be attached to. These software packages will provide a much more powerful tool when it comes to trying to identify whether the DNA of a particular person, defendant or victim, is represented within a complex mixed profile, however, they will not assist with the question of correct attribution or in determining the significance of the results vis-à-vis an alleged action over a defence alternative.
It is also important that there is raised awareness amongst those responsible for advising defendants and preparing cases for court, that their previous knowledge may no longer apply and some of the old convenient assumptions may no longer be correct. Ideally this should exist from the interview stage, to ensure that the forensic results are not misrepresented in questioning, right through, if necessary, to testimony at court. Otherwise we risk an increase in the number of occasions in which courts process criminal cases without accurately understanding the evidential value of the forensic results that form part of the prosecution.