Fri, 22 May 2009

Growth of the National DNA Database increases the risk of miscarriages

Brian Costello's Are DNA ‘cold hits’ resulting in miscarriages? is an analysis into whether false DNA matches will lead to miscarriages of justice, if they have not done so already. He questions whether chance DNA matches are occurring but are not being recognised.


Due to the current size of the NDNAD [National DNA Database], full profile chance matches (“adventitious matches”) are now actually expected to have occurred. A truly staggering 2.5 trillion odd comparisons have been made: 500,000 (Crime Scene Samples) x 5,000,000 (Subject Samples) = 2,500,000,000,000. Under ideal conditions, a full SGM+ profile is generally predicted to occur with a frequency of 1 in 1 trillion (although a figure of 1 in 1 billion is routinely given in court as it is perceived to be highly conservative in favour of the defence). With the NDNAD at its current size, and taking the 1 in 1 trillion chance match figure, a simple mathematical analysis indicates that two full SGM+ matches are expected to have occurred between a Crime Scene Sample and an unconnected Subject Sample. Put another way, it is expected that two suspects have been wrongly identified as linked to a crime scene by a false match.

Unfortunately, a simple mathematical analysis will not give the true picture. Two factors will increase the probability of adventitious matches: firstly, the condition of crime scene samples may lead to incomplete profiles; and secondly, individuals who are related are more likely to share the same profile than unrelated individuals.

A crime scene sample can be uploaded onto the NDNAD where results have been generated at only eight out of 10 loci (loci are DNA analysis sites), and a speculative search can be conducted where only six of 10 loci have produced results. Where results are obtained from less than the full 10 loci, the random match probability is reduced; it is more likely that a match will occur by chance alone. The comparison of incomplete profiles suggests that the prediction of only two adventitious matches could be a significant underestimate. Depending on the number of incomplete Crime Scene Samples uploaded, the number of expected adventitious matches could easily run into double digits. It would also appear that the problem of adventitious matches is set to increase with the expansion of low copy or low template DNA tests (“LtDNA”). LtDNA testing frequently produces incomplete profiles. If these incomplete profiles are uploaded to the NDNAD, or speculatively searched against it, the probability of obtaining adventitious matches will increase. Even more concerning is the fact that in a LtDNA test the entire DNA sample collected from a crime scene can be consumed, preventing further testing that would exonerate a person wrongly linked by an adventitious match.

People who are related share genetic material derived from their common ancestors. The closer the relationship the greater the chance their DNA profiles will match. In court, this would be expressed by a reduced match probability for a scenario that a relative committed the crime (e.g. match probability 1 in 1 billion for an unrelated individual, but one in several hundred thousand for a full sibling). It is a known fact that the NDNAD contains the profiles of a large number of related individuals. However, due to the level of duplication on the database – currently estimated to be around 13% of all samples – it is quite possible that two related (or unrelated) individuals share a full SGM+ profile, but the adventitious match has not been identified as it has incorrectly been attributed to duplication.


Given that further adventitious matches have been predicted, but none have been identified, there must be real concern that an innocent person has been wrongly convicted on the basis of an adventitious match; perhaps because they were not prepared to identify a family member and so entered a guilty plea, or perhaps because unlike Mr Easton they did not have compelling evidence of their innocence. If a miscarriage based on an adventitious match has not occurred yet, it appears likely it will occur in the future as the NDNAD grows ever larger. Greater use of the LtDNA technique will further increase the probability of such a miscarriage.

Brian Costello is completing a third six period of pupillage at One Inner Temple Lane and as a result of his concern is researching the discrepancy between predicted and identified adventitious matches. As part of that research he is interested in hearing from any defence practitioners who have:

If that's your case, then get in touch with him at

(Hat tip: Are DNA ‘cold hits’ resulting in miscarriages? was published in the excellent CrimeLine newsletter.)

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Thu, 21 May 2009

Mobile phones, tracking, data remanence, dataveillance and privacy - updates

Mobile phone tracking

The cost of having your movements tracked by your university? A free iPhone. The School of Social Informatics at Tokyo-based university Aoyama Gakuin is giving students free iPhones that will be 'used as a tracking device with which the university can control if its students are physically on campus or not (the main goal is to prevent cheating during roll calls).'

Last month I wrote about the mobile phone as self-inflicted surveillance. If you don't carry this voluntary electronic tag, then you must have something to hide. Frank Stajano, a senior lecturer at in the Computer Laboratory at University of Cambridge who was involved with developing the Active Badge system at ORL twenty years ago has just written an article on location privacy issues.

Data remanence and information accountability

The security research team in the Computer Laboratory at University of Cambridge ran an experiment to test what happens when data deleted from the cloud. They 'found that most [of 16 social-networking, blogging, and photo-sharing web sites] failed to remove image files from their photo servers after they were deleted from the main web site. It’s often feared that once data is uploaded into “the cloud,” it’s impossible to tell how many backup copies may exist and where, and this provides clear proof that content delivery networks are a major problem for data remanence.' The issue of data take-down is being looked into by the W3C Social Web Incubator Group.

Data take-down is only one tactic addressing a larger issue, and one that is not working well as the Cambridge research has shown. An interesting and more general approach is one based on information accountability. See my post Forgetting. Consequences. Bruce Schneier also posted a useful essay on Privacy in the Age of Persistence.


Earlier this week... Making location data an integral part of user experience and having user's data reside in the cloud, with the mobile device acting as a cache, were two key directions participants to the Mobile User Experience (MEX09) conference saw the industry moving to. The mobile industry has to take much more responsibility for the dataveillance and data remanence scenarios it is creating.

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Thu, 07 May 2009

Sky News Sunrise on Thursday at 8.15am

Jacqui Smith pre-announced in The Observer, she will publish this week the government's plans for the destruction of the DNA profiles and/or DNA samples of innocents. Details are currently lacking. A first welcomed step in complying the European Court of Human Right's ruling would be the bulk destruction of the DNA profiles, DNA samples, fingerprints and associated PNC records of innocents.

Tomorrow, Thursday, at 8.1015am I'll be interviewed by Eamonn Holmes on Sky News Sunrise about my experience getting off the National DNA Database (NDNAD).

Update 1 - From press reports, the Home Office plans include:

(The consultation document has still not yet been published.)

Update 2 - I arrived at the Westminster studio early. This allowed time for a recorded interview (I don't think this interview was used), with Joey Jones, about my views on the NDNAD and the announced changes. The destruction of the DNA samples is a positive step, but the retention of DNA of innocents for years is not acceptable.

While I wait, Vernon Coaker shows up with three minders. Two of them write down what he says when he's on air. I make a mental note to debunk some of his more outrageous claims such, e.g., the large size of the NDNAD helps with crime detection. The detection rate remained about the same when the number of individual profiles on the database doubled. What makes a big difference is the number of DNA profiles of crime scenes, not of individuals. (See Ten myths about the NDNAD for more myths debunking.) A few minutes after the quartet leaves Sky News, one of the minder comes back to pick up a document she had forgotten on a table; unfortunately no journalist had noticed this possibly interesting material!

Then it's eventually my turn. The set up is very disconcerting as there's no one else in the studio and the only feedback is audio. I sit in a fixed chair and am told to look at a spot which is between the camera lens and a red light situated above it. Two strong lights are directed at whoever is in the chair, hence the regular blinking. I listen to the previous segment while staring at this dark spot behind the lights and above the camera. A voice introduces itself as the producer and asks me if I hear the audio feedback fine and eventually it all starts. At no point can I see what image is broadcast or the reaction of the interviewer. Joey Jones told me earlier it was likely to be Eamonn Holmes, but not being that familiar with his voice I do not really know who's interviewing me.

I had prepared some points I wanted to talk about. Some I mentioned in the recorded interview (why such a large database, because this database state is keen on collecting as much data as it can on us; it is a criminal intelligence database for the purpose of crime detection), many others I didn't (databases have mistakes, are accessed illegally, get forgotten on trains, etc. DNA can be used to identify children and parents as well, the samples and profiles are used for research without consent, etc. and some practical advice: the current system of the 'exceptional procedure', that if you're on the NDNAD you should go to the new Reclaim your DNA website, and in any case you must respond to this consultation.) As Eamonn Holmes was under the impression that my DNA profile was still on the NDNAD, I explained several of the actions I had to take in the two years it took me to manage to eventually successfully reclaim my DNA. I had the impression we had just started, but several minutes had already gone and it was all over! So I had the time for much less than I was hoping to communicate. Click on either of the two pictures to download the video (16.5 MB), if you must.

On my way out, I bumped into Helen Wallace of GeneWatch UK, the leading UK organisation providing independent information on genetic technologies, on her way to do some interviews. Read GeneWatch's reaction to the government plans at Home Office drags its feet on DNA database removals.

Mistaken suspectDNA Campaigner

I wonder who decides on the captions identifying people on TV? I didn't think 'Former suspect' was neutral enough when this was used in an earlier appearance. This time, the caption changed through the interview. It started with 'Mistaken suspect' and finished with 'DNA campaigner'. The former is obviously wrong and is likely why it was changed, but the latter is still a shortcut: DNA is not a campaign. I am campaigning, with many others, to ensure that innocents are no longer treated as 'yet to be convicted' and that means full compliance with the ECtHR ruling condemning 'the blanket and indiscriminate nature of the powers of retention of the fingerprints, cellular samples and DNA profiles of persons suspected but not convicted of offences'.

Update 3 - The consultation Keeping the right people on the DNA database has now been published. It closes on 2009-09-07. With more than five million profiles on the NDNAD, about one in ten persons in the UK, either you're on it or you likely know someone who is. After a critical reading of the documents, do respond to voice your views. For reliable independent information on most aspects of the NDNAD, check GeneWatch UK.

Until the consultation closes and the government decides what it will do, hopefully more in line with the spirit of the unanimous ruling of the ECtHR, the 'exceptional' rule still apply. If you're innocent and on the NDNAD, write to the chief constable of the force that arrested you to reclaim your DNA.

First published 2009-05-06; last updated 2009-05-07.

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