back to article Controversial DNA profiling technique approved

An independent review of the science underpinning DNA forensics done on tiny samples has today declared the controversial technique sound for use in investigations. The report highlights poor handling of samples by the police and forensics officers, and recommends new training to reduce the risk of contamination. The probe …


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  1. Anonymous Coward


    I seem to remember seeing 6% quoted as the chance of getting a full profile via this technique. Which basically means it's worthless, as all you'll have is lots of false positives with the real culprit *possibly* somewhere among them.

    This may not be such a problem if you have a small database size, and if the evidence isn't a particularly important part of the case, but I suspect if you're using LCN techniques you probably haven't got much to go on.

    Given a larger (full population?) DNA database the situation would be even worse - based on a partial match from a LCN generated profile you could wake up one morning being accused of something you had nothing to do with, and potentially have a very difficult time proving otherwise as there'll be 'DNA evidence' against you.

    And even if you do prove your innocence you may well have been arrested, charged etc.

    DNA evidence is never as solid as people like to think, and in this case is about as substantial as wet tissue.

  2. Mike Tyler


    Often wondered if this technique for dna amplification could be used to take dna from some innocent, say one wacky home secretary and introduce it into a crime scene along with maybe a finger print from the same person. As they say neither DNA or fingerprints are ever wrong are they ?

  3. Pete Silver badge

    The tech's OK, the social problems are very bad

    All this technique does is establish a "link" between the person who's DNA is detected and the object, or person, it was found on. There's no qualitative information about how close that link is: simply that it exists.

    So, for example. If you hand someone a bank-note, it has your DNA on it. The quantity is minute, but it's enough to say that you (as well as hundreds or thousands of others) have touched that piece of paper.

    Now, if that note is found on a terrorist - or their blown-up corpse, there's a link established between you and that person.

    If you happen to be associated with a "likely" group of people, who for whatever reason are under suspicion of a possible involvement (note the fuzziness of these previous statements), then having your DNA as evidence could be all that's needed to "prove" you were involved. The evidence presented in your trial could be along the lines of:

    "We've been monitoring Mr/Ms X as an associate of <terrorist> and have conclusive DNA proof of their connection"

    This technology is actually negative progress in terms of criminal investigations. Instead of the old "round up the usual suspects and see who talks", the usual suspects are now anybody that the immensely widened net now trawls in. The chances are good that *someone* of the hundreds of suspects can be nicked for something associated with the case. Great for clear-up figures and headlines, terrible for catching the perpetrators (who are still at liberty, to do it all again)

    Like a drunk with a lamp-post, LCN is more use to prop up a shakey case than to provide illumination about who dunnit..

  4. James

    Flaw with DNA profiles not LCN

    I can't help but think that the problem with DNA matching is not to do with LCN techniques but the fact it only looks at about 13 different stretches of the human genome. Sure, the likelihood of a DNA match for the whole genome is tens of billions to one but that's not what is measured and stored.

    The small amount of data in the current NDNAD records only gives odds in the thousands against erroneous matching. As the NDNAD expands, this limitation is going to crop up more and more often.

  5. Graham Marsden


    So, even more opportunities for planting DNA at the scene...

  6. Anonymous Coward
    Anonymous Coward


    The reason they look at only a few key markers is because these are the areas shown to differ from one person to another. Remember that 96% of the hunman genome is shared with chimpanzees so that's 96% which can be ignored immediately.

  7. Luther Blissett

    Worthless review

    That was quickly done wasn't it - so much crime, so little time! But specious, one suspects. Unless you read VERY carefully and conservatively you will miss what is being said. No wonder it was trumpted by BBC radio this morning - CRIME LATEST: SUSPECT TECHNIQUE WALKS FREE.

    Here is what you need to understand the babble.

    "scientifically robust" - theoretically ok, but totally dodgy in the hands of numpties.

    "appropriate for use in police investigations." - but not in determining whether to prosecute or to submit as evidence.

    "A separate review of past convictions by the Crown Prosecution Service found no problems" - a fundamental principle of natural justice is that no man is allowed to be judge in his own trial. Hello, CPS...?

    "DNA techniques offer the police service an invaluable tool in identifying and eliminating suspects" - illustrating the postmodern approach to policing: the criminal is the one who ends up with the conviction (our bases say so), not necessarily identical with the one who committed the crime. Is it still an offence to impersonate a police officer? Hello, 999...?

    "He recommends setting up national standards for training, equipment, and analytical procedures." - Apple pie and motherhood rule. The real meaning is that as used as present, it contradicts all the above claims. Illustrating the postmodern approach to scientific scrutiny - first principle: don't bite the hand that feeds. Hello, is there a natural philosopher in the lab...?

    "Juries should be given special guidance by a new independent expert body on how to interpret LCN evidence". Clearly forgetting to add "in other words people like me, who can turn around Home Office jobs at a good speed and with the right answers", and quite oblivious to the current unsatisfactory status of "expert witnesses" in giving evidence - especially in relation to statistics and probability. A professional chancer then. So is there an expert witness in the black box...? Or is it a cat and black.

    I submit that no "expert" be allowed anywhere near a witness box unless no-one can be found who can present a case as to the probability of that witness being any less than 100% correct.

    "Juries should be given special guidance" - as loaded a construction as the prosecution could wish for. If a prosecution rests on technical evidence, then the significance of that to the prosecution case should be put in open court - from the judge presiding to the public gallery. Otherwise juries may as well be given guidance mafia-style. Whacky Jacky has her way.

    "Too much focus has been put on reassuring the public" - illustrating the postmodern approach to public interest scrutiny bodies, unless the quote has been pulled out of context.

    "It has been used in several high profile investigations worldwide" - and remains inadmissible in several countries.


    @James > "Remember that 96% of the hunman genome is shared with chimpanzees so that's 96% which can be ignored immediately."

    Ignoring your typo, there is a murder mystery by Edgar Allen Poe you haven't read - it might change your mind about that 96%.

  8. A J Stiles
    Thumb Down


    From the article: `[Caddy] said: "I found that the technique, as developed by all the forensic suppliers, is scientifically robust and appropriate for use in police investigations."

    `If the review team had found fundamental problems with LCN DNA, it could have meant dozens of convictions going back to 1999 would have to be reexamined.'

    Translation: It's bollocks, and we know it is, but in the present climate we really can't risk casting doubt on DNA evidence -- especially not if it might call into question nearly 20 years' worth of convictions and ruin all the grooming we've done on the public to get them to accept DNA as infallible.

  9. Anonymous Coward
    Thumb Down

    Unsound science used in a punitive manner

    Even the developer of the technique had contamination problems, and he had graduate and post-graduates doing the lab work.

    If these people have problems doing the job how can you expect somebody in the average lab to do it?

    All samples sent in should be sent with 'blind' samples so that the lab has to determine which, if any, match.

  10. Wayland Sothcott Bronze badge

    Everyone is unique

    This is used as the argument about why DNA is so good, because Genes are so unique. But it is not the same as the tecnique being good, they deliberately confuse the two. You can't clone a human from the info in the genetic fingerprint. However using pseudo science to baffle courts into convictions is the aim. It saves a lot of money if suspects can always be proved guilty. They are planning Titan prisons for all the extra people they intend to put away.

  11. Chris C


    So it's back to guilty unless proven innocent, then? And since you can't really prove innocence (it's impossible to prove a negative, after all)...

    "DNA techniques offer the police service an invaluable tool in identifying and eliminating suspects in crime investigations"

    Am I the only one scared by the word "eliminating" in that statement? Especially as you brits are now just about as good as us yanks in eliminating/terminating people who just don't quite look, act, or think the "right" way.

  12. Richard Silver badge

    The science behind LCN does work. But it's fundamentally flawed.

    It is based on amplifying incredibly small samples.

    However, every person leaves very small samples of their DNA on everything they touch, and it's very difficult to fully clean any object.

    Therefore, the ONLY possible use for LCN DNA profiling is in 'Cold cases', where they've got a fairly clean slide from an old case that they can re-examine.

    Even then it's unreliable, as you're just as likely to match with the lab assistant as with the criminal!

  13. Jerry

    It's evidence innit?

    The DNA match is used for two purposes.

    Firstly to identify possible suspects based on a DNA match between a crime scene sample and record stored elsewhere. This use simply says to the investigators that so-and so should be investigated as a possible suspect in a case. They will then get lots of other evidence to make a case. Usually this will be more than enough to prosecute without any reference to the DNA match.

    The only problem here is that they may have a number of matches using LCN techniques so the investigator's workload increases.

    The second use is where the DNA match itself is presented as primary evidence. This has many difficulties and it is unlikely a purely DNA prosecution would succeed. The defense could raise all sorts of arguments related to possible cross-contamination, statistical likelyhood etc. etc.

    DNA is evidence, no dispute. What is in dispute is what weight it has in a prosecution (or defense) case. What is in particular dispute here is LCN as opposed to full sample DNA.

    I am pretty certain that LCN will be mostly used for screening and supplementary evidence purposes while full profile DNA will be used for the same purposes but may also be used as a lead item of evidence. If DNA evidence is used that way I don't see a problem.

  14. Dave

    A thought or two here

    This is a technique that is technically difficult to perform, needs a good deal of manual skill and concentration, and even then is only as good as the collection of the sample.

    The wages in the now privatised forensic science area are barely above minimum wage. Your average checkout person on the tills in Tesco gets paid considerably more, and the wages in the retail sector aren't traditionally considered high.

    Put the two together.

    You worried yet?

    You bloody well should be

  15. Dr Teeth

    DNA Bombing:- a simple solution for criminals

    I'm very surprised that I have seen very little discussion on a very simple way to beat the DNA tests.

    If I were to break into a place and wanted to cover my DNA tracks, I would do a little planning first. Over a period of several weeks, I'd go around some random hotels and or hospitals and collect used vacuum cleaner bags.

    Then I'd pool their contents and put them in small explosive devices (such as a bug bomb style), creating DNA Bombs.

    Once I've performed my criminal act (gloved of course), I'd set off the DNA bombs at the scene of the crime.

    It would be interesting to see how the forensics teams cope with thousands of different random DNA samples.

    Even if they did track my DNA to me, how easy would it be to prove that I was actually there and not just another piece of DNA shrapnel?

    ...That is assuming they aren't busy tracking the DNA of known drug dealers who happened to use the same hotels which supplied the vacuum cleaner bags...

  16. Steve Bush
    Black Helicopters


    1. perhaps low whatsit corresponds to the old water divining sticks where the water locating "expert" deflected gullible peoples to the idea that it was the stick and not him who decided where the water was

    2. if this is used for suspect elimination then how come all those cases appeared to depend on it? or did they not?

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