A6 Murder DNA evidence

[reg1965]

Hi Vic
Hope you had a nice holiday. (not with XL I hope!!)

Re your post #60

The main difference with this case (Simpson) compared to Hanratty as you correctly say is the direct route of contamination.
It is my view, and it has been corroborated by Professor Allan Jamieson that the vast majority of analysts working in criminal DNA analysis are employed by the FSS. It has been difficult (and I hate the term whistleblower) for defence teams in legal cases to obtain genuinely top class expert advice and witnesses as nearly all of them, hitherto, worked for the prosecution.
I believe that this was the case in Hanratty. I mean no detriment to Dr Martin Evison, the appellants expert witness in Hanratty (2002), but was he truly an expert in advanced DNA techniques and the problems involved, at that time? I don't think so. He only set up his RCHI program at the University of Sheffield in 2004.

Dr Evisons page at UCL (University of London, visiting) can be found at;

http://www.jdi.ucl.ac.uk/cs_network/cs_contacts/evison.php

By the time of the Simpson and Hoey cases (2007) the defence teams could call on Professor Jamieson's Forensic Institute team to give both expert advice and defence witness testimony about LCN DNA.

Whereas in Hoey and Simpson the problems of mixed profiles were exposed, this was not done in Hanratty, although similar mixed profiles must have existed due to the very nature of the technique used.
Consider the DNA profiles of Valerie Storie and Michael Gregsten as mention in the Court of Appeal judgement. How were these obtained? In the case of Valerie Storie that would not be difficult as she is still alive (does anyone have any information as to when this was done?) but how did the FSS obtain a certain profile of Mike's? (any help here? I am sure that someone has mentioned it on here or in the other place). His body was not exhumed to my knowledge.

Therefore, why have you exclaimed "The prosecution had stated that the chances of the profile belonging to anyone else other than Mr Simpson was 1 in 40 million!"? I'm convinced that the profile was Simpsons, it's just we know how it got there.

I was only quoting from newspaper reports on the case. But I assume that because the DNA evidence was all the prosecution had to go on they had to make the most of it. This was reinforced by Dr Whitaker who stuck to his guns and stated that he stood by what he had said. This was, I again assume, part of the CSI effect that DNA seems to have on juries.

I do not have access to the transcript of the Simpson case (yet) but here is what Justice Weir had to say about Dr Whitaker in his judgement in Hoey (2007 paragraph 63 (in full))

I was concerned about the manner and content of the response of Dr Whitaker to these criticisms. He was most unwilling to accept that the continuing absence of international agreement on validation of LCN (unlike SGM+)or the variations in the way in which it was being implemented in different countries should be any impediment to the ready acceptance by any court of the Birmingham approach. I found him inappropriately combative as an expert witness and his unwillingness to debate constructively the various matters put to him was unhelpful in the extreme. By contrast, his colleague Dr Gill, while understandably concerned to endorse the views of Dr Whitaker where he properly could, was willing to carefully consider the propositions put to him by Mr Pownall QC and, where appropriate, to disagree with his colleague on important issues both general and specific to the case. In my view it was extremely fortunate that the prosecution decided late in the day to call Dr Gill as his evidence greatly helped to inform and bring some objectivity to the debate.

Again as with the cost of the DNA analysis, I was only quoting from newspaper reports of the Simpson case. Bearing in mind that the case was not initiated from police investigation but from purely a cold case DNA gamble (match to taxi drivers from the DNA database) it does seem in this case that the gamble was an expensive one. Also this was just the cost of the DNA work, not the whole cost of the case which I cannot find (as yet).
The one thing I would say here is that if DNA evidence is the starting block for initiating an expensive investigation, with all of the expectations of the victims loved ones and anxiety of the accused (and thier loved ones) accrued then I say no.

I cannot help you any further with the internal standards of replication although PCR is the replication/amplification phenomena used in all SGM/LCN/LT techniques. Hope that helps?

Kind regards
Reg

[Dupplin Muir]

Missing DNA

Hello Victor

You make an interesting point, but not perhaps in the way you intended. It seems that contamination of DNA evidence is the norm, even today when the police and forensic scientists are aware of the need to avoid it. Yet we are meant to believe that nearly 50 years ago, when no-one had any idea about DNA testing, the cops and forensics people managed to avoid leaving any of their DNA on the samples! Also, what about DNA from other people who had been in the car prior to the crime? People shed skin-cells constantly (I've heard it claimed that most household dust actually consists of such skin-cells!), and even if the car had been thoroughly valeted it would not get rid of all this extraneous DNA.

The problem with the DNA results in the A6 case is that they are just too convenient: Gregsten's, Storie's, Hanratty's and no-one else's! From the prosecution's point of view, to admit that (say) three other sets Of DNA had been found would allow Hanratty's team to argue that since there has clearly been contamination, perhaps Hanratty's DNA is part of that contamination, and that the killer is one of the three unknowns. Also, as Reg has pointed out, there was very little of Hanratty's DNA present (otherwise they would not have needed to use LCN) so the prosecution could not argue on a quantitative basis.

As for Dr Whitaker being willing to accept the possibility of contamination in the Templeton Wood trial, I imagine this is rather different from accepting contamination where it might imply that an innocent man was hanged, especially given the reluctance of the authorities to acknowledge that they have ever convicted an innocent person, much less executed one.

It also seems that while Dr Whitaker is indeed very well-regarded by police and prosecutors, he is not thought of quite so highly by other DNA specialists.

DM

[JamesDean]

Consider the DNA profiles of Valerie Storie and Michael Gregsten as mention in the Court of Appeal judgement. How were these obtained? In the case of Valerie Storie that would not be difficult as she is still alive (does anyone have any information as to when this was done?) but how did the FSS obtain a certain profile of Mike's? (any help here? I am sure that someone has mentioned it on here or in the other place). His body was not exhumed to my knowledge.

Hi Reg,

You raise a good point about the DNA of Michael Gregsten. I had already noted (to myself) the somewhat unusual phrasing of certain references in the text of the judgment to the Gregsten forensic evidence.

Here are the relevant paragraphs and the text referencing Gregsten's DNA is highlighted by me for clarity:-

113. The knickers arrived at the Metropolitan Police Laboratory (MPL) on
23 August 1961 where they were examined by Dr Nickolls, the director and his
assistant, Henry Howard. They were found to be stained with seminal fluid in
the area of the crotch and at the back for five inches upwards from the crotch.
Vaginal fluid from Valerie Storie was also present. There were smaller
quantities of seminal fluid of blood group AB assumed to have come at some
earlier stage from Michael Gregsten. Although the laboratory records are not
dated, the notes are numbered sequentially and we are confident that the
knickers were examined almost immediately and in any event no later than
23 September 1961 when the notes show that certain samples taken from Peter
Alphon were examined at the laboratory. The handkerchief came to the
laboratory on 25 August, was screened for blood and semen and, none being
found, seems to have been put to one side.

125. But that is to ignore the results of the DNA profiling. With regard to the knicker
fragment we have what Dr Whitaker would describe as a typical distribution of
male and female DNA following an act of sexual intercourse leading to the
obvious inference that the male contribution came from James Hanratty. For that
not to be the case we would have to suppose that the DNA of the rapist, also of
blood group O, had either degraded so as to become undetectable or had been
masked by James Hanratty’s DNA during the course of a contaminating event.
Moreover, we would also have to suppose that Valerie Storie’s DNA had
remained in its original state, or at least detectable, and had escaped being
overridden by DNA from James Hanratty. The same would have to be true of the
DNA attributed to Michael Gregsten. Finally, we must visualise a pattern which
is wholly consistent with sexual intercourse having taken place in which Valerie
Storie and James Hanratty were the participants.

Note the use of the word assumed in paragraph 113 and attributed in paragraph 125.

I'm not convinced that Gregsten's DNA was ever positively identified.

Any thoughts?

Regards
James

[Victor]

Hi all,

Reg, are you including in the CSI effect the fact that some seem to take "the chances of the profile belonging to anyone else was 1 in 40 million" being equivalent to "there's only a 1 in 40 million chance of X not being the criminal"? as they are very very different.

You raised a couple of interesting points:-
Mixed profiles - Simpson and Hoey had mixed profiles including contamination profiles, whereas Hanratty had only 3 profiles (which links to Dupplin Muir's post). I've seen Gregsten's profile "overlooked" as in identified and eliminated and have wondered whether any lab technician's (or Jennifer Wiles') profiles have been treated in a similar way, but there is no evidence for this.
MG's profile - where did it come from? In 1997 they used JH's mother and brother for comparison purposes, maybe the used MG's children?
Whitaker seems to be what can only be described as arrogant in the extreme - and certainly his behaviour taints his evidence but I don't think we've got to the Prof-Meadows-lying-to-cover-failings stage.
Costs - any argument is more general than specific to this case as it would seem to apply to all sorts of investigative techniques, like fingerprinting and blood types.

DM,
Just need to highlight this..."The problem with the DNA results in the A6 case is that they are just too convenient: Gregsten's, Storie's, Hanratty's and no-one else's!". Too convenient indeed, but there's the possibility that any contamination 40 years ago would have decayed to the point of below minimum detection limits, and the indications of only examining the liquid stains on the knicker fragment mitigate against this.

Stephen Fry and the QI Team have stated that dust isn't even mostly skin cells but I'd need to check that, or at least find a source.

Also the second paragraph is weakened by the fact that any contaminant DNA profiles would need to be identified if possible - samples from all the present day technicians would be available.

Vic

ps. I had a great holiday thank you - it wasn't with XL fortunately.

[Victor]

Note the use of the word assumed in paragraph 113 and attributed in paragraph 125.

I'm not convinced that Gregsten's DNA was ever positively identified.

Any thoughts?

Hi James,

I completely agree with assumed, but not so much with attributed although that could go either way.

[caz]

Hi James, Victor,

Can you tell from the context whether the word assumed comes from the undated notes made in 1961 or at the time para 113 was written? If it's the former, I don't think it would be so much of a problem, because it would have to have been an 'assumption' then, based on Valerie's account of the night's events, rather than scientific proof. (I hope to God they at least confirmed that Gregsten's blood group was indeed AB! )

As for attributed, I agree with James that it does sound a tad imprecise for comfort. But could it be scientist-cum-legal 'speak' to distinguish a match obtained from the actual person (alive or dead - in the previous sentence we get Valerie Storie's DNA and DNA from James Hanratty) from a match obtained from relatives?

Treading softly here because my skills are not in the science department at all, but I can sometimes help with English usage and interpretation.

Love,

Caz
X

[Victor]

Hi again,

I agree with Caz, assumed in this context implies to me that they found some AB semen, spotted that MG was AB, and from VS's evidence decided it was his.

Re-reading it gives me the impression that attributed to is taking the "assumption" one step further - we assumed it was MG, so now we've attributed the AB-type DNA profile to him.

If you add in para 108 "These comparisons confirmed that the male contribution to the profiling from the knickers almost certainly came from either a son of Mary or a brother of Michael" - "male contribution" singular?

Of course this contradicts the whole thrust of para 125 quoted in fulkl by James above.

[caz]

Hi Victor,

If 'the male contribution' in the context of para 108 merely meant the specific contribution assumed (that word again) to have come from the offender, maybe it was not thought necessary to mention MG's contribution to the profiling at this point.

The relevant wording in para 125 does seem to be fairly unambiguous:

'Moreover, we would also have to suppose that Valerie Storie’s DNA had
remained in its original state, or at least detectable, and had escaped being
overridden by DNA from James Hanratty. The same would have to be true of the DNA attributed to Michael Gregsten.'

A nonsensical statement unless DNA attributed to MG had indeed survived along with VS's and JH's. It tends to imply that at the very least there were two male DNA profiles to work with. It doesn't bear thinking about if the one that wasn't JH's was just assumed to be MG's, without any further confirmation. Would the respective blood groups have been confirmed again along with the DNA analysis? (You see how woefully ignorant I am about what can and can't be ascertained after 40 years.) The point being, we do at least know that the rapist's blood group was found early on to be O and not AB.

Love,

Caz
X

[JamesDean]

Would the respective blood groups have been confirmed again along with the DNA analysis? (You see how woefully ignorant I am about what can and can't be ascertained after 40 years.) The point being, we do at least know that the rapist's blood group was found early on to be O and not AB.

Blood type can be established from DNA with potentially greater accuracy than was possible using serological tests in 1961. The DNA analysis of 1997 would have identified the blood type as part of the profile of any DNA found on the fragment. That one of the male DNA could be ascertained to correlate with blood type AB does not prove that it belonged to Michael Gregsten, although logic says it is likely, without comparing the profile to genetic material known to be from MG or his family (parents/children). I do wonder if it was taken for granted that the male DNA of blood type AB was MG's without any further comparison being made. The use of the words assumed and attributed in paragraphs 113 and 125 of the judgment, as mentioned in my earlier post #63, suggests this to be the case.

If an assumption was made along those lines, does this raise any cause for concern?

Regards
James

[caz]

The use of the words assumed and attributed in paragraphs 113 and 125 of the judgment, as mentioned in my earlier post #63, suggests this to be the case.

If an assumption was made along those lines, does this raise any cause for concern?

Thanks James.

'Suggests' is fair enough, but we don't know for sure. 'If' can be a very big word.

If and when 'experts' talk in absolute terms, their objectivity can be called into question; when they use words that act as caveats and qualifiers, the strength of their evidence can be doubted. Damned if they do and damned if they don't.

If an assumption was made, and by some freak chance the AB DNA did not come from MG but some other unknown male, we would just have to add another couple of layers to the mystery in order for JH to have been innocent: rapist's original O DNA not found on knicker fragment; MG's AB DNA not found on fragment; JH's O DNA transferred to fragment via a contamination event; unknown male AB DNA found on fragment for unknown reason.

We are still pretty much stuck with the rapist's blood group being O.

I don't think they could have done much else back in 1961 but assume it was MG's AB semen in addition to the rapist's O semen. But I do take your point about it being a potential cause for concern, if this was compounded by at least one more assumption at the later DNA analysis stage.

Let's hope they did obtain DNA from a suitable Gregsten relative for comparison. That would seem the obvious thing to do, if they knew JH's team would be looking for no less than a belt and braces job.

Blimey, pass the headache pills.

Off for a long weekend - see you Monday. Be good.

Love,

Caz
X

[Victor]

"The knickers arrived at the Metropolitan Police Laboratory (MPL) on 23 August 1961 where they were examined by Dr Nickolls, the director and his assistant, Henry Howard. They were found to be stained with seminal fluid in the area of the crotch and at the back for five inches upwards from the crotch. Vaginal fluid from Valerie Storie was also present. There were smaller quantities of seminal fluid of blood group AB assumed to have come at some earlier stage from Michael Gregsten."

To me these sentences say that in 1961 they found 2 sets of semen, one was blood type AB so they assumed it to be MG's and from that point forward described it as "attributed to MG", the other was the rapists (subsequently in 1961 found to be blood type O)

Now that's not a problem IF they subsequently positively identified the AB-semen as MG's via the DNA profile.

To me this sentence "The same would have to be true of the DNA attributed to Michael Gregsten." doesn't say that MG's DNA was positively identified, but it also doesn't say that it was.

A nonsensical statement unless DNA attributed to MG had indeed survived along with VS's and JH's. It tends to imply that at the very least there were two male DNA profiles to work with.

This quote from Caz I agree with but we've got those qualifiers in there.

Is it a cause for concern? Yes it is!

[reg1965]

Hi All

Re JamesDeans post #69

Blood type can be established from DNA with potentially greater accuracy than was possible using serological tests in 1961. The DNA analysis of 1997 would have identified the blood type as part of the profile of any DNA found on the fragment. That one of the male DNA could be ascertained to correlate with blood type AB does not prove that it belonged to Michael Gregsten, although logic says it is likely, without comparing the profile to genetic material known to be from MG or his family (parents/children). I do wonder if it was taken for granted that the male DNA of blood type AB was MG's without any further comparison being made. The use of the words assumed and attributed in paragraphs 113 and 125 of the judgment, as mentioned in my earlier post #63, suggests this to be the case.

If an assumption was made along those lines, does this raise any cause for concern?

I found an interesting piece in Woffinden (1997. p400) where before James Snr died the Hanratty family found James' blood donor card. It seems he was not only O secretor but also rhesus negative. Geoffrey Bindman (their solicitor) contacted a consultant haematologist who told him that seminal fluid did not contain the rhesus factor. The government at the time, furnished with this information stated it did not throw any new light on the case. Fair enough there then...... but...was any mention made of this in the Court of Appeal judgement. No. (also in what circumstances was Alphon excluded!!!! lack of knowledge of LCN on the part of the appellant perhaps? I'll come back to that later in this post.)

Another point. Say we take that the profile of Mike had been obtained from an immediate family member as being the case. It just makes the exhumation of James (and his aunt) all the more of an odious act. If the exhumation was at all unnecessary it just makes it all the more vindictive and surely an act that is more of a show than of any scientific worth.
This just adds to the assumptions and the subjectivity of the interpretation of the mixed profile that Dr Whitaker had obtained from the fragment of Valeries underwear in 1997. (In my opinion the DNA evidence obtained from the hanky can be discarded as we know that it was James')

As for mixed profiles consider the following;

From paragraph 114 of the Appeal judgement (2002)

On 7 October 1961 a suitcase containing James Hanratty’s clothing was seized from the home of his girlfriend, Louise Anderson. It was received at the laboratory on 9 October. Amongst other items it contained a pair of dark pinstriped trousers (part of the Hepworth suit) and a green jacket and trousers. Some hairs and fibres were removed from the outside of the dark trousers as was a sample from a seminal stain on the inside of the fly. A suggestion, which has not been contradicted, is that the seminal stain may have been washed out and retained in the form of a liquid. On 13 October, the laboratory received samples of James Hanratty’s blood and saliva. It was only at this point that the police became aware of his blood grouping. The records are incomplete but there would seem to be no reason for any of James Hanratty’s items of clothing or for his intimate samples to be present in the laboratory at the same time as the knickers or the handkerchief. There is, of course, the possibility that all the exhibits were stored in the same place, albeit separately packaged, which, it is submitted, might have provided the opportunity for secondary contamination. Dr Nickolls is dead. Mr Howard is still alive though in poor health. His recollection is that the dangers of contamination were recognised even in 1961 and that the practice was to take elementary precautions such as making sure that clothing from victim and suspect were not examined on the same day.

(my enboldening)

and paragraph 116

As a result of correspondence between James Hanratty’s then solicitors and the DPP, arrangements were made for the pathologist, Dr Grant, to have access to James Hanratty’s intimate samples and also to certain of the exhibits. It appears from the records that Dr Grant examined the green jacket and trousers on 28 December 1961 and Valerie Storie’s slips and knickers the following day. It was on this latter occasion that a portion of the crotch area of the knickers was removed and thereafter, as seems clear, stored separately from the other exhibits including the knickers from which it had been excised. As also seems clear, a fragment of the excised portion was retained by the laboratory having first been placed in a small envelope made of cellophane and sellotape which was in turn put into a small brown envelope and the small envelope into a larger envelope before being treasury tagged to a laboratory file. It was so placed when rediscovered in 1991.

This is were real reasonable doubt enters the ring. Persistence of DNA betweeen the analysis sessions is not only possible but very probable. Any items worn by James would be full of his DNA. It only takes a few cells to have been present on the lab work surface for transfer to have taken place. Even if todays standards of clean room examination are applied there still exists the possibilty of transfer of contamination. Let alone in 1961 even allowing for Mr Howards 'best practice'. (p 114 above)

and a partial fragment from paragraph 120

Dr Evison seems to accept that in the case of the knicker fragment the contaminant would have to be semen.

This is the killer statement in the whole process as far as I am concerned. It is therefore obvious that if Dr Evison had been up to speed with LCN DNA analysis he would not have needed to make this statement.
In previous DNA analysis techniques (including SGM+) the contaminant would not have been picked up as was shown in 1995 (because of the high supra 150 RFU) when the tests were inconclusive. Under LCN, any DNA by whatever transfer or contaminant would have been picked up!
That still does excuse the fact that a mixed profile would still be the best that Dr Whitaker had to work with and the question is how could he ascertain who's profile was which. At what RFU level(s) was he working and on what basis did he dismiss the other (obviously present) profiles? How many replicate samples were produced and what was the result of these? Was a voting system introduced to pick the best of 3 (or 10, imagine if the consensus vote is wrong), I'm not joking this is how LCN is done. This is why we hear of profiles being perhaps billions against the suspect not being profile X!

Regards
Reg

[Victor]

I found an interesting piece in Woffinden (1997. p400) where before James Snr died the Hanratty family found James' blood donor card. It seems he was not only O secretor but also rhesus negative. Geoffrey Bindman (their solicitor) contacted a consultant haematologist who told him that seminal fluid did not contain the rhesus factor. The government at the time, furnished with this information stated it did not throw any new light on the case. Fair enough there then...... but...was any mention made of this in the Court of Appeal judgement. No. (also in what circumstances was Alphon excluded!!!! lack of knowledge of LCN on the part of the appellant perhaps? I'll come back to that later in this post.)

How about...it wasn't mentioned because it was irrelevant? The Hanratty family solicitor investigated, and the person he contacted said it wasn't relevant. It's not mentioned in the judgement, but that doesn't mean it wasn't discussed, the judgement is a summary of relevant information presented by either side.

PLA was excluded because they didn't find any of his DNA in the profiles.

Another point. Say we take that the profile of Mike had been obtained from an immediate family member as being the case. It just makes the exhumation of James (and his aunt) all the more of an odious act. If the exhumation was at all unnecessary it just makes it all the more vindictive and surely an act that is more of a show than of any scientific worth.
This just adds to the assumptions and the subjectivity of the interpretation of the mixed profile that Dr Whitaker had obtained from the fragment of Valeries underwear in 1997. (In my opinion the DNA evidence obtained from the hanky can be discarded as we know that it was James')

This doesn't follow at all. They did use DNA from JH's mother and brother for the initial comparison and found a match, therefore to confirm the result they needed a definite sample of DNA from JH. If the initial match to ma and bro had been negative then they would not have needed to exhume. Surely this is blatantly obvious.

As for mixed profiles consider the following;
From paragraph 114 of the Appeal judgement (2002)

Why not enbolden this too..."His recollection is that the dangers of contamination were recognised even in 1961 and that the practice was to take elementary precautions such as making sure that clothing from victim and suspect were not examined on the same day."

This is were real reasonable doubt enters the ring. Persistence of DNA betweeen the analysis sessions is not only possible but very probable.

Big leap of logic there - the paragraph confirms Mr Howard's comment about not being examined on the same day. And you are making countless assumptions about the isolation and cleaning policies of the laboratory with no evidence to back it up.

Any items worn by James would be full of his DNA.

"full of"? It's just not possible to say that without lots of qualifiers like "provided the items weren't washed", "dependant upon how frequently James bathed", "dependant upon the time between wearing and examination" etc...

It only takes a few cells to have been present on the lab work surface for transfer to have taken place.

Rewording that slightly...
It is an absolute necessity for a few cells to have been present on the lab work surface for the possibility of transfer to have taken place.

Even if todays standards of clean room examination are applied there still exists the possibilty of transfer of contamination. Let alone in 1961 even allowing for Mr Howards 'best practice'. (p 114 above)

Yes. The possibily of contamination is extremely difficult to eliminate, that is why it was admitted and examined.

and a partial fragment from paragraph 120
"Dr Evison seems to accept that in the case of the knicker fragment the contaminant would have to be semen."

This is the killer statement in the whole process as far as I am concerned.

I agree, it is a killer statement.

It is therefore obvious that if Dr Evison had been up to speed with LCN DNA analysis he would not have needed to make this statement.

It is not a statement by Dr Evison!

It impies that Dr Evison accepts the statement of the prosecution!

Are you saying you disagree with the statement? If so, why?

In previous DNA analysis techniques (including SGM+) the contaminant would not have been picked up as was shown in 1995 (because of the high supra 150 RFU) when the tests were inconclusive.

No DNA was detected (above the threshold) in 1995.

Under LCN, any DNA by whatever transfer or contaminant would have been picked up!

Not true. There is a threshold below which DNA is not detected in sufficient quantities - in other words there is a minimum sample size for LCN.

That still does excuse the fact that a mixed profile would still be the best that Dr Whitaker had to work with and the question is how could he ascertain who's profile was which.

He had samples of VS and JH DNA with which to compare!

At what RFU level(s) was he working and on what basis did he dismiss the other (obviously present) profiles?

First part - I would like to know too. Second part - "obviously present" - I presume you are talking about VS and MG's profiles as there are not necessarily (and in fact it is stated that there are not) any others.

How many replicate samples were produced and what was the result of these?

Good question, I want to know too - but it is asking for more details of the technique.

Was a voting system introduced to pick the best of 3 (or 10, imagine if the consensus vote is wrong), I'm not joking this is how LCN is done. This is why we hear of profiles being perhaps billions against the suspect not being profile X!

Pure speculation. You might not be joking but you are giving the worst possible interpretation you can. For all you know the LCN process might be the SGM+ process with "repeat 29 times" replaced with "repeat 34 times". And yes that is me giving the best possible interpretation to contrast with your worst.

Regards,
Vic.

[Dupplin Muir]

An interesting article

Hello all

The following article comes from The Journal Online, the online members magazine of the Law Society of Scotland:

http://www.journalonline.co.uk/article/1003857.aspx

It is not an overstatement to say that the advent of forensic DNA analysis has revolutionised the place of scientific evidence in court. The public perception, judged by a wholesale acceptance of the National DNA Database (NDNAB) as a “Good Thing”, underlines the need to educate people, and especially those involved in the investigation and prosecution of crime, of the potential dangers that accompany the undoubted benefits of this technology.

DNA analysis is one of the most scientifically robust techniques to be placed before a court. A series of legal and scientific challenges has honed the collection, processing, analysis and evaluation of DNA evidence to reduce the possibilities for erroneous results. Already some other evidence types have benefited from the advances in evidence evaluation that followed the challenges to DNA. On the other hand, some identification disciplines with a long pedigree in court, but little or none in science, have signally failed to catch the wind that is now blowing through forensic science. DNA has reminded us that no matter how small or large the numbers, all scientific evidence is probabilistic, and only an exclusion of involvement can be regarded as certain.

Overwhelming odds?
For a DNA profile 10 areas of DNA are analysed, rather like examining only 10 shelves in a library. Maybe 10% of people have a Harry Potter book. Five per cent have Alice in Wonderland. Thirty per cent have A Brief History of Time (and 0.01% understood it!). The probability of someone having all three books is 1/10 x 1/20 x 3/10 = 3/2000, or approximately 1 in 666. You can see that no matter how many books you choose to include in the search, the probability of finding a person with all of those books will get smaller, but never reach 0.

Two features of DNA evidence that can be viewed as its major benefits also produce its greatest potential dangers: specificity and sensitivity. Specificity can be considered as being similar to what used to be called discriminating power, in effect how useful it is in telling two people apart. In DNA this is usually expressed as the match probability: the probability that the DNA profile would be obtained by choosing a person at random from the population. This number is now routinely in excess of 1 in a billion (1 thousand million). Unfortunately this is usually wrongly perceived as meaning that the odds are 1 billion to 1 that the accused is the perpetrator. This even has a name: the prosecutor’s fallacy. (The defence have their very own, different, fallacy too.) Juries, now fully conversant with forensic science via CSI, Waking the Dead and Silent Witness, add these compelling figures to the compelling figures of their TV heroes to conclude that “guilty” is the only sound choice. We have now even coined the term “CSI effect” to recognise the (damaging?) effect of these programmes on juries.

Sensitivity is a measure of how little DNA we need to perform analyses and produce a profile. Until recently DNA was recovered from visible stains like blood splashes or semen stains. Then we started to collect samples, usually by swabbing, from areas where we may expect to find DNA from body fluids, e.g. cigarette ends, cutlery, spectacle frames. The introduction of Low Copy Number DNA (LCN) has seen us now enter an era where single pieces of DNA may produce profiles; that is, less than 100 picograms (0.0000000001g) of DNA.

A little part of yourself
To understand why that may be a problem it is useful to consider that each of us have about 1014 cells in our body, each with a full DNA profile packed inside them. We lose a number of these cells every minute of every day (and night – that’s what keeps a family of bed bugs in food). Everywhere you go you probably leave your DNA. And here’s the problem: your DNA goes places you’ve never been. This is probably one of the main differences between DNA and fingerprints. A correct fingerprint identification, on a fixed object, may establish that you were at a particular point, but DNA can be transferred from you to someone else and from that someone to somewhere else you may never have been.

When we had blood or semen stains that could be seen, we were perhaps a little more confident that this established a link between the source of the stain and the location of the donor. But if you can walk through the supermarket and one of your cells blows into a vehicle or onto a surface a distance away, then it has literally distanced itself from you.

Combine the compelling specificity with molecular level sensitivity, and a population DNA database, and you have a potential scenario where your DNA is found at a crime scene that you have never been near. Your name and address are obtained from the database and the police informed that there is a 1 in a billion match probability. On questioning you say, truthfully, that you have never been in that location. What is the policeman thinking? “Mistake”, “Sorry to have troubled you, sir”, or “Liar”?

Inevitably, you become a suspect. Is it just possible that this apparently compelling evidence will be placed alongside some other circumstantial evidence (can YOU account for, and prove, where you are every hour of every day?) to gain a conviction?

Contaminated evidence?
As much as the DNA technologies created controversy and challenges when they were introduced, LCN DNA has produced its very own set of problems. Not least among these is the limited number of providers of this technology. In many cases they are working with old, degraded, or sub-microscopic volumes of material.

Many, if not all, of these old, or “cold”, cases occurred before DNA forced a rethink of the possibilities for contamination of evidence. Exhibits were collected with little regard for who was handling them or the possibilities of cross contamination from suspects to items via the investigating officer. Even the laboratory environment or procedures would not be designed to protect against the transfer of such low amounts of material. This was not negligence; it just didn’t consider the possibility of such traces becoming important.

In forensic science the fact to be established is that the DNA profile originated from the material recovered from a crime scene or a suspect, not the investigator, the laboratory, packaging, or analytical instruments. A “negative control” is set up by simply processing a “blank” sample that has no DNA. All being well, this control will not show any DNA. The presence of DNA in the negative control illustrates that there has been a source of contamination in the analytical method. It does not, of itself, show where that occurred, merely that it has. The tradition over many years has been, for very sound reasons, that anything found in the “negative control” invalidates the analysis.

There are now some who argue that this principle cannot be applied to LCN DNA analysis, because even in a tightly controlled analytical procedure a significant number of supposedly negative controls give a positive result, i.e. they indicate the presence of DNA.

The issue of course is that if it cannot be established that the DNA has been introduced during the analysis, how can any of the DNA found in the crime stains be shown NOT to have come from the procedure rather than the scene?

Lastly, the very small amounts of DNA and the vagaries of the method mean that it is frequently the case that replicate samples, that should produce the same results, don’t. The process gets around this difficulty by simply taking a vote of three replicates. DNA types found in two of the three are regarded as real and counted in the “consensus” profile. We use the consensus result as the basis of the statistical calculation of how rare a combination is in the population at large – in effect the probative value of the DNA evidence.

Probability and uncertainty
Now imagine that we take 10 of these consensus results for different areas of DNA to calculate the match probability. This process will yield a statement of the form, “the probability of this profile coming from X rather than some unknown, unrelated person is…”, and then a number that is frequently of the order of billions, but with no statement of the confidence that we can place in that result despite the clear, and probably measurable, uncertainty that must exist.

This is not an argument for the abandonment of any or all DNA methods. It is a warning of the dangers of not understanding the potential for honest error and margins of error. These new techniques are undoubtedly of tremendous value as intelligence in criminal investigation. In cold cases the requirement for other corroborative evidence must reflect the increased uncertainty in the LCN results.

The scientific issue is the degree of confidence that can be placed in the results and the consequent opinion. The legal issue is whether the destructive techniques meet the requirements of physical evidence acceptable in court.

Professor Allan Jamieson is Director of The Forensic Institute, Glasgow

From this we see that it is indeed possible to get a LCN profile from a single cell. Note also that Dr Jamieson says "..the requirement for other corroborative evidence must reflect the increased uncertainty in the LCN results." In other words LCN DNA by itself is not sufficient.

I suspect that Hanratty's appeal came at an unfortunate time, when the police had pretty well a monopoly of DNA expertise, particularly in LCN DNA, with the result that the team in charge of his appeal could not really counter Dr Whitaker's testimony. Nowadays there are several well-respected laboratories that can provide defence counsel with experts capable of critiquing prosecution evidence, and it certainly seems that police DNA experts are getting a much rougher ride in court than they used to.

DM

[reg1965]

Hi Vic

Re your post #73. You made 15 points and I will deal with each one in turn.

1) I mentioned the rhesus negative findings in reponse to JamesDeans post #69 (as I referenced). As blood types were mentioned in the Appeal Courts judgement and some doubt exists as to the exactitude of the owners of said blood it seems relevant. As to Alphon, how was his DNA profile obtained and again how could his profile be dismissed competely among all of the other profiles in the mix? Remember we are dealing with LCN and do not know the rfu threshold used. It could be sub 10rfu's for all we know!!

2) HOW WAS MICHAEL GREGSTENS DNA PROFILE OBTAINED TO ASCERTAIN ABSOLUTELY THAT HIS DNA WAS PRESENT? sorry for shouting but this should be blatantly obvious!!

3) See 7 below

4) See 7 below

5) Absolutely. It depends on a lot of things but the plain fact is that anyones clothing is going to contain skin cells no matter what ones ablution policy may be. Even in clean room examinatons they still exists a very real possibility of contamination. This happens in the vast majority of LCN processes. Let alone 1961 as I stated in the post you have referenced.

6) I was actually giving the 1961 team the benefit of the doubt. But point taken nonetheless.

7) The possibility of contamination using LCN is not only possible but is a by product of the sensitivity of the technique. If this has not been explained plainly enough by now then I cannot help any further.

8) Nothing here.

9) Fair enough, but as you stated earlier we do not know what was actually discussed as we do not have access to the full transcript therefore it would be puerile to argue the toss when the semantics are effectively the same.
Yes I do disagree as one cannot tell from the DNA which particular bodily tissue the DNA eminated from. DNA is DNA from whichever cell it was taken!

10) Wrong. DNA was detected. It was inconclusive.

11) Sorry but it is true. That is why LCN is used. Only 100 picograms of DNA is needed. The threshold can be as low (or the amplification as high, it is an equivalent) as one likes it will still show up. The problem is how does one interpret the allele peaks at such low levels! Plus then how can replicate samples be verified by more than 2 analysts?

12) This is nonsense. In a mixed profile how could you tell who's profile was whose? You would have to subtract, say VS's profile which could remove a part of JH's. Where are you then?

13) There would undoubtedly be many numbers of individual DNA's present in the mixed profile. It would be nye on impossible to tell which was which. That is why they produce so many replicates to test individual profiles against. I suggest that Dr Whitaker was just guessing.

14) Read the article Dupplin Muir found in his post #74

15) Speculation? I think you will find that SGM+ at 34 amplification cycles is LCN. SGM+ has been validated for obvious reasons. Look it up somewhere, not Wikapaedia though please. I am an MSc research student so don't fob me off with references to Wikapaedia alone.

regards
Reg