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DNA - John C. Kirk

Mar. 11th, 2006

10:48 pm - DNA

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This afternoon I went along to give my DNA/fingerprints to the police. This is related to the Sally Anne Bowman murder from last September, and the basic profile for the murderer is "male, white, 20-40, living/working in South Croydon". So, the police have been asking for people to come forward voluntarily to give samples that can be used to narrow down the search a bit; more info here.

In my case, I doubt that I'd be a serious suspect, but I do fit the basic profile (male/white/31/living nearby), and I'm happy to help out, so I went along. The testing area has been open for the last couple of weeks, but the main reason it's taken me so long is that it's not convenient in the morning (you can't have eaten/drunk anything for 20 minutes beforehand, and I normally have breakfast just before I leave the flat), and that I'm not normally home by 10pm in the evening. Anyway, it finishes tomorrow evening, and I have a (rare) weekend without SJA duties, so this seemed like a good time.

Bruce Schneier discussed this in his blog a couple of weeks ago. Generally speaking, I respect his views on security a lot - I've bought three of his books, and read two of them (!) cover to cover; the third one ("Applied Cryptography") was the core textbook for the cryptography module in my MSc. However, in this case I'm inclined to disagree with him, because there seems to be a kneejerk reaction against any hint of privacy concerns, where the government is collecting data on citizens. Having said that, his main objection seemed to be that people were being coerced into giving DNA samples, rather than that it was an intrinsically bad thing. I think that this recent User Friendly strip expressed the counter-argument quite nicely.

So, as I say, I went along to the church hall where the police were collecting samples. All in all, I was there for about 25 minutes (only queueing for about 2 minutes).

Step 1 was to show my ID and go through a short questionnaire. There were some fairly common questions (e.g. name/address/date of birth), and then some that were specific to this case (did I ever meet the victim, have I seen any of the evidence lying around). Things got a bit more blurry when they asked questions about other people. Firstly, they wanted to know about anyone else who lived in my flat (N/A), and about my neighbours - the idea seems to be that their next step is to go round seeing people at home who didn't volunteer to be tested, so they're trying to work out which houses to visit. More specifically, they wanted to know whether there were any other people living near me who matched the profile of the murder suspect. I figured that this is information that ought to be in the census (which it is a legal obligation to answer), so I mentioned my upstairs neighbours. Similarly, there were a couple of questions that asked whether I or anyone I know has been the victim of sexual assault, or a peeping tom, or anything like that. This was where I was vaguer than the police would probably have liked - I said that I knew of one person who'd been involved in a situation like that, but that I wouldn't give them the name/address, because it wasn't up to me to reveal the details.

Step 2 was to go to a different person, who checked my details again. Actually, I don't really remember this person adding much to the process, since he just repeated a couple of the same questions (name/address/date of birth), and gave me a packet to carry to step 3.

Step 3 was fingerprints. I started by getting a photo taken, holding up a board at chest height with a number written on it. It's a lot like the scenes I've seen in films where people are arrested, except that this was only a front shot (not "turn left, turn right"). The guy asked me to take my coat off for that (which I was happy to do), but I kept my CEA hoodie on (with the hood down). As for the fingerprints themselves, he checked that I wasn't wearing any rings (my watch wasn't a problem), and told me to roll my sleeves up. In retrospect, I think I should have just taken the hoodie off at this point (to avoid stretching the cuffs), but no biggie. He had a black pad, and he rolled some fresh ink onto it before we started. He then told me to relax my hand, then he guided my fingers to the appropriate place. Firstly, each finger/thumb was printed individually - this involved rolling it from side to side on the pad, and then again on the piece of paper. (The finger next to the little finger is the tricky one, because the other fingers catch on the edge of the table.) Then the thumbs were done again, rolling from front to back, to get the full length. Finally, the fingers were done in groups of four (i.e. one hand at a time). This did leave my hands rather messy (as you'd expect), but they have a supply of wet paper towels to clean up with, which are surprisingly effective, as well as dry paper towels to dry off with.

Step 4 was the actual DNA sampling. This involved two samples, apparently to guard against one of them being tampered with, so that someone can't say "That wasn't me!" I'm not quite convinced by this logic, since I don't see why it would be much harder to tamper with both, but I don't see that it makes me any worse off, so I don't have a problem with that. For each sample, he put a swab inside my mouth, and did three strokes at the bottom then three strokes at the top (next to the jawline). This didn't hurt, but it was slightly uncomfortable - not something I'd do for fun, but not a big deal either.

There were a few more standard questions at this point, and my habit of reading the forms upside-down came in handy:
Policeman: "Middle name?"
Me: "Crispin, spelt C-R-I..."
Policeman writes "K-R-I"
Me: "No, that's C-R-I"
Policeman: "Yup"
Me: "Not K-R-I"
Policeman: "Ok"
Me: "So you need to change that K to a C"
Policeman: "Ah, right" (changes it)

The most important thing here was to sign the consent form. (This actually happened before the samples were taken, but I've left it until the end because it deserves a longer discussion.) The form had three sections, and the idea is that I would sign either A or B, while the police would sign section C. Section A said "I agree for my sample to be used in this case, then destroyed afterwards". Section B said "I agree to my sample being stored in the national database, and being used in the prevention and detection of other crimes. NB Once consent has been given it cannot be withdrawn." (I'm paraphrasing from memory, since they kept all the forms, but that's the basic gist of it.)

Now, all of the publicity surrounding this sample-gathering has emphasised that the samples will only be used for this one case. Some people don't believe this (e.g. one of the commenters to Schneier's blog, who thinks that the police will weasel out of it by destroying the physical samples and keeping the digital copy), but that's certainly the claim. So, this question caught me by surprise, and my immediate thought was "Hmm, if I go with section A, that's going to look a bit suspicious". However, the policeman then emphasised that this is entirely up to me, and that he recommended section A. He said that if I went with section B then I don't know what the sample might be used for in the future, so I might find the CSA (Child Support Agency) tracking me down for my illegitimate children. He then left me to think this over while he filled out some of his other paperwork.

I considered this, and eventually (after a couple of minutes) decided to go with section B. Bottom line, I don't have any axe murders in my past, nor am I planning to commit any in the future, so I don't see any downside to doing it. Hopefully there are two advantages to this:
a) I came across as someone with a clear conscience, rather than someone with dark secrets.
b) If they do any similar sample gathering in the future then I don't have to turn up, because they've already got mine.

So, I told the policeman my decision, and the conversation went like this:
Me: "Ok, I'm going to go with section B."
Him: "Are you sure?"
Me: "Yeah, I don't have any illegitimate children running around, so I should be fine."
Him: "Well, not yet, anyway... I know which option I'd pick, but it's up to you."
Me: "Yup, I'm sure."
So, despite the privacy concerns that people have, I do want to emphasise that the police weren't trying to coerce me into joining the national database; quite the reverse, in fact.

I may regret this in the future (with the "no opt out" clause), and I think that other people should know about this question in advance to avoid being blindsided, but life's all about making choices.

While this may not be the best analogy, I've been thinking about an old storyline from the Superman comics, where Lex Luthor had a Kryptonite ring to keep Superman at bay. He eventually stopped wearing it when it gave him cancer and he had to have his hand amputated. Anyway, Superman got hold of it (in a lead box), and gave it to Batman for safekeeping - he was concerned about the possibility that he might turn evil in the future, and so he wanted someone he could trust to have the means to stop him in that scenario. I don't think I'm likely to go off the rails, but if it did happen then I'd want to be caught (or rather, the "me now" would want the "evil twin me" to be caught). People who know me well enough can probably fill in a few of the blanks there, but I don't want to elaborate in a public post.

Anyway, all in all I thought it was quite an interesting process, and if anyone else is reading this who lives nearby then you should probably consider whether to head down there tomorrow.

Comments:

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From:elvum
Date:March 12th, 2006 10:21 am (UTC)
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Did they explain how voluntarily collecting DNA from random members of the public helps them track down the culprit? Are they hoping that every young white male in Croydon bar one comes forward?
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From:johnckirk
Date:March 12th, 2006 11:31 am (UTC)
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They didn't really explain any of the motivation yesterday, presumably because they didn't need to convince the people who'd turned up for it. But quoting from the news report I linked to:

Even though DI Cundy knows the killer is highly unlikely to voluntarily offer to be DNA tested, he believes hundreds of potential suspects can be quickly eliminated from inquiries, crucially freeing up police time.

In theory, I'd say that it is more efficient to have people going to them, rather than the police going house to house, partly because they can have a "chain" in effect (e.g. I'm getting my fingerprints taken while you have your DNA sampled), whereas if you have the whole team in one place then most of them will be twiddling their thumbs. Having said that, this report says that only 114 people turned up on the first day, so I don't know how busy they were overall.
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From:elvum
Date:March 12th, 2006 01:21 pm (UTC)
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I really don't buy that - if they have suspects, why haven't they just asked them for samples? And why tie up so much police and lab time testing (potentially) tens of thousands of irrelevant people? Actually I suspect that the real reason the policeman discouraged you from signing up for the national database is because they *don't want* to send the samples to the lab if they don't think you're a suspect.

Basically I can't see any sane reason for going through with such a fantastically expensive exercise - either they're being very stupid or they're hiding their real motives, and in neither case do I want to give them my DNA.
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From:sammoore
Date:March 12th, 2006 02:14 pm (UTC)
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I'm with Steve on this one.

Whats the point in DNA testing random people? There's quicker and cheaper ways to elimanate you than that, that's to ask what you were doing at the time, what your motive might be, etc. The old fashion way.

The real culprit is hardly likely to volunteer his DNA and all they are doing is eliminating perhaps 0.1% of the population at enormous expense.

Steve is right, either that's very stupid or they have a different motive, either way my DNA is staying in me.
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From:johnckirk
Date:March 12th, 2006 03:04 pm (UTC)
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I'm not a police spokesman, so I can only speculate about their reasons for doing this. That said, I'd guess that they've been following the traditional methods for the last 6 months, and that they've moved onto the DNA testing because that hasn't worked.

Speaking for myself, I've checked my diary/calendar, and I don't have anything listed for that evening (about 2am on Saturday night/Sunday morning), so I assume that I was alone in my flat, i.e. without any alibi. I'd like to think that I don't come across as "creepy serial killer", and there is the whole "presumption of innocence" thing, but I also think that it's in my interests to co-operate; that way I'm potentially helping myself as well as the police, and I have nothing to lose because I have nothing to hide.

I do also wonder whether there are some civil liberties issues involved, e.g. if the police can't specifically target people who were accused of assault but never charged, so they're doing a huge dragnet instead.

As for the expense, I'm guessing that this will act as a test case to some extent - if it actually works, then they'll probably repeat it in the future. When the police were chatting to each other yesterday, I heard one of them say "If he does this again...", presumably meaning "If the killer attacks someone else". And I suppose that would be one argument in favour of maintaining the national database - there's a one-off cost to gather samples, rather than going through the same process on an annual basis.

Speaking of the big database, one discussion that came up in Bruce Schneier's blog is the accuracy of DNA testing, in terms of the number of data points that are necessary. That's not my field of expertise, but it does seem to me that having a larger database will reduce the likelihood of errors. E.g. "we get 100 matches from this test, so we need to examine those 100 people more closely" vs "there may be 100 matches out there, but you're the only one we know about, so you're our prime suspect".
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From:susannahf
Date:March 12th, 2006 03:50 pm (UTC)
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I doubt it will be used as a test case. There was a good test case many years ago when DNA fingerprinting was in its infancy. I think it was a rape/murder somewhere in England. They had evidence implying that the killer was a local man, which narrowed it down to a few thousand.

They caught him because he got a colleague (who lived outside the area) to pose as him and go for a test. After a couple of months, the guy got suspicious, and admitted to the police, whereupon they arrested the killer for obstructing police enquiries, tested him and convicted him. They actually already had him on their suspects list before the dragnet but had eliminated him because of the "negative" result.
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From:johnckirk
Date:March 12th, 2006 04:18 pm (UTC)
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Hmm, interesting. That may be why they wanted two forms of ID (one with a photo, one with an address), to guard against a repeat of that.
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From:rjw1
Date:March 12th, 2006 04:48 pm (UTC)
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Steve is right, either that's very stupid or they have a different motive, either way my DNA is staying in me.

i think its just so they seem to be doing something. since they obvioulsy have no idea.
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From:gaspodog
Date:March 12th, 2006 02:25 pm (UTC)
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Interestingly, if I gave consent to have my DNA databased and my brother did not, they would get his anyway by virtue of having mine! (Identical twins and all that)
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From:johnckirk
Date:March 12th, 2006 03:07 pm (UTC)
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That is an interesting point, and I'm not sure what the fairest way to handle it is. Some kind of veto perhaps, where you both need to give consent? Mind you, your DNA wouldn't be linked to your brother's name/address, so I suppose that offers some protection.

Doing a quick websearch, this page says that identical twins don't necessarily have the same fingerprints; I don't know whether my fingerprints and DNA are now going to be stored together, or separately. And this page has the Jerry Springer scenario where identical twins were involved in a paternity suit, so the judge ordered them to split the cost of child maintenance.
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From:johnckirk
Date:March 12th, 2006 03:09 pm (UTC)
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Oops, I forgot to mention my other thought on the "consent" issue - I can imagine it getting a bit more complicated if one of you committed a crime, and therefore didn't need to consent to DNA sampling.
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From:bazzalisk
Date:March 13th, 2006 06:31 pm (UTC)
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I seem to recall a case a few years ago when they caught somebody because his brother donated volluntarily, got a partial match, and they pulled his family in for questioning as a result.
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