A6 Murder DNA evidence

[Victor]

From this we see that it is indeed possible to get a LCN profile from a single cell.

There are a couple of points to pick up from that summary. First, the above is slightly misleading, the minimum threshold is 100pg

From http://news.bbc.co.uk/1/hi/sci/tech/3607993.stm
"The mass of a single cell of the E coli bacterium is 665 femtograms, the researchers say in the Journal of Applied Physics.

A femtogram is one-thousandth of a picogram, which is one-thousandth of a nanogram, which is a billionth of a gram."

Therefore if we assume 1 cell is 2/3 of a picogram you roughly need 150 cells to be detectable.

Secondly, "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." is blatantly wrong. 1014 cells weighs roughly 1014 x 2/3 picogram = 676 picogram. A person weighs in the region of 50Kg or 50,000 grammes. 1picogram = 10E-12g. I assume that quote should say each of us has 10 to the power of 14 cells in our body.

More later, things are going crazy with work...

[Victor]

Hi Vic

Hi Reg,

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!!

What I meant was that the rhesus state of the blood could not be detected from a sample of semen, so has absolutely no bearing on the conclusions, therefore wasn't mentioned in the judgement.

PLA gave a DNA sample, and none of the alleles of his profile were found in the knicker fragment so the conclusion is that PLA was not the rapist.

I don't know where you are getting the "all of the other profiles in the mix" comment from, there were only 3 found - MG, VS and JH.

And yes, we do not know the rfu threshold used, so negative speculation about it is just that - negative speculation. I cannot argue against it because I don't know, and neither do you.

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!!

Yes it is blatantly obvious, and I don't know. I made a very similar comment in post #71. The conclusion I reached is that there is no definite conclusion either way, but it is a cause for concern.

My comments were directed at your critism of the exhumation and especially this "surely an act that is more of a show than of any scientific worth". The point being that the initial comparisons yielded a high probability of a match, and therefore to confirm they exhumed JH to get a direct sample of his DNA.

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.

Yes, but the samples on the knicker fragment were semen and vaginal fluid, therefore any discussion of skin cells in what may have been a wash of the Hepworth trousers is irrelevant.

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

OK, but as we can see from post #76 it's now risen to 150 cells, and yes I'm aware that a flake of skin contains multiple cells, so we now talking about particles rather than cells.

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.

Yes but you seem to be arguing about "lots of profiles in the mix" when there were only 3 specifically mentioned. You cannot say LCN is extremely sensitive and is therefore at risk of high levels of contamination, therefore there were profiles from contaminants. You cannot assume contamination to have taken place without seeing the raw experimental data.

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!

Quite right, we do not have the full transcript, but we have the legally binding judgement, which was compiled from discussions of legal representatives and expert witnesses, and when it says that both sides accept that the contaminant would have to be semen then you have got to provide some evidence if you are arguing that it wasn't. It's not a case of semantics, it's a case of you arguing against the experts on both sides.

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

In other words, the DNA was not detected in sufficient quantities so as to reach the RFU threshold, ie, my qualifier in brackets was correct and you are wrong to disagree.

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?

<pedantry warning>So if you have 99 picograms of DNA then it would not be detected!

You are agreeing with me that there is a minimum sample size - and that minimum size is 100 picograms.

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?

This just shows your lack of understanding of the technique. They use alleles in the highly variable part of DNA where the chances of VS and JH having the same alleles are equivalent to finding identical snowflakes.

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.

No, I just completely disagree with the first line. No matter how many times you argue the possibility or probability of contamination that is not proof that contamination definitely happened. Especially when you are arguing against the known conclusion (note "conclusion", not "results") presented in the judgement.

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

Read, absorbed. "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."

And that's the point isn't it, there is corroborative evidence in the form of VS!

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

Yes! LCN is more than just 34 cycle SGM+. SGM+ defines a procedure and minimum standards that must be met for each PCR cycle.

Here's your quote "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." now it starts with the word "Was" but is missing a question mark, so maybe you meant to say "A voting system was introduced..."

KR,
Vic.

[JamesDean]

Quite right, we do not have the full transcript, but we have the legally binding judgement, which was compiled from discussions of legal representatives and expert witnesses, and when it says that both sides accept that the contaminant would have to be semen then you have got to provide some evidence if you are arguing that it wasn't. It's not a case of semantics, it's a case of you arguing against the experts on both sides.

Hi Vic,

This is an interesting point as the judgment assumes the contaminant to be semen and thereby limits the possibilities for contamination. This is one of the flaws of logic that I cannot accept. I don't think that Dr Evison truly accepted that the contaminant had to be semen but I believe he was bullied into accepting that hypothesis.

The judgment states Dr Evison's compliance with that hypothesis in suitably vague terms. As highlighted by me in the quote below, "Dr Evison seems to accept ... !"

120. Mr Mansfield submits against that background that the respondent has not been
able to exclude the possibility of contamination. In making that submission, he is
supported by Dr Martin Evison who is a senior lecturer in Forensic Biological
Anthropology in the Department of Forensic Anthropology at The Medico Legal
Centre in Sheffield and has many academic achievements and publications to his
credit. He told the court that he had not been able to exclude “the realistic
possibility of contamination”. Dr Evison seems to accept that in the case of the
knicker fragment the contaminant would have to be semen. That really limits the
possibilities to (1) contact between the knickers and the Hepworth trousers and
(2) contact between the contents of the broken vial and the fragment held on file.

To his credit Dr Evison never accepted the notion, proposed by the prosecution witnesses, that contamination was considered to be only a remote possibility.

121. That said we should also record that not one of the respondent’s witnesses
excluded the possibility of contamination. They have expressed themselves in
different ways but the general tenor of the evidence has been that they each
considered the possibility to be remote. That, of course, has to be contrasted
with the opinion of Dr Evison who never moved from his original position as
stated in this judgment.

I think that Dr Evison was outnumbered but that doesn't make him wrong!

Regards
James

[Victor]

Hi Vic,

This is an interesting point as the judgment assumes the contaminant to be semen and thereby limits the possibilities for contamination. This is one of the flaws of logic that I cannot accept. I don't think that Dr Evison truly accepted that the contaminant had to be semen but I believe he was bullied into accepting that hypothesis.

Hi James,

Why is it a flaw in logic? The sample was a semen stained knicker fragment, and logically you'd expect the DNA profiles discovered to be those people who'd had sex, ie, VS and MG and the rapist. Three profiles were found therefore you have the problem of working out where the rapists semen got to if you suppose that JH wasn't the rapist and his DNA was introduced as a contaminant.

To use words like "bullied" you are pre-supposing that JH is innocent and have closed your mind to the possibility that he was the rapist.

The judgment states Dr Evison's compliance with that hypothesis in suitably vague terms. As highlighted by me in the quote below, "Dr Evison seems to accept ... !"

To his credit Dr Evison never accepted the notion, proposed by the prosecution witnesses, that contamination was considered to be only a remote possibility.

I think that Dr Evison was outnumbered but that doesn't make him wrong!

Regards
James

Again only if you cast Dr Evison in the hero role and judge JH to be innocent when interpretting the evidence can you use words like "to his credit [he] never accepted the notion".

Contamination was considered to be a remote possibility because of the highly improbable situation where JH's DNA magically obliterates the rapist's DNA but leaves behind VS and MG.

The major question that needs to be asked is:- If JH wasn't the rapist, where has the rapists semen got to?

[caz]

Hi James, Victor, All,

I’d be interested in hearing your thoughts regarding the DNA evidence used to convict Ronald Castree of the 1975 murder of Lesley Molseed. There appear to be one or two parallels with the DNA evidence in the A6 case.

In the Real Crime documentary shown on ITV last night it was claimed that just one bit of forensic evidence from 1975 had survived, in the form of an envelope containing a small piece of tape used on an item of Lesley’s clothing to pick up any fibres etc that may have been left by her killer. Because semen had been found on her knickers, it was thought there might just be a chance that some had been lifted up onto the surviving tape, which could provide the killer's DNA profile. According to the documentary it was the first time a DNA profile had been obtained in this way. The case was 25 years old in 2000, and was described as the oldest ever worked on at the time (?). They also had only one shot at it because the tape would be destroyed in the process.

In the event they struck lucky and discovered sperm heads in the extracted material and obtained the vital DNA profile. But no match was found in the data base and their work was kept secret so as not to alert the killer. The final breakthrough came in 2005, when Ronald Castree was accused of rape by a prostitute. A routine DNA swab gave them the match they had been waiting for and he is now serving life.

Is there any suggestion that sperm heads were looked for or found on the A6 knicker fragment? If none were found, should they have been? Or would the additional 15 years in this case have provided a reasonable explanation?

And crucially, does anyone have any doubts about the process leading to Castree being positively identified as Lesley Molseed's killer from that little piece of tape? No potential flaws in the DNA technique? The findings perfectly valid?

Love,

Caz
X

[caz]

Hi Victor,

I agree with you that certain observations made on this thread about the appeal judgement give the definite impression of coming from a position of believing that Hanratty was innocent, and therefore believing that the DNA evidence was not only inconclusive or unreliable, and should not have been admissible - it must actually have been wrong. This is a step too far, because it relies on the original case evidence for support and there is nothing there, nor anything about the DNA findings themselves, to indicate that the latter did in fact identify the wrong man or fail to identify the right one.

The very best that can be argued dispassionately and without bias or gut feelings creeping in is that the original case evidence was not strong enough to make the conviction 100% safe, and the DNA testing would not have been reliable enough on its own to render it safe. If that was all that was being said around here, I'd have some sympathy for the view and call it stalemate unless anything new turned up. But it's not just a case of claiming Hanratty should not have been found guilty without more damning evidence. People seem to be using this supposed lack of ultimate proof to make him innocent - which it very clearly doesn't.

Love,

Caz
X

[JamesDean]

Why is it a flaw in logic? The sample was a semen stained knicker fragment, and logically you'd expect the DNA profiles discovered to be those people who'd had sex, ie, VS and MG and the rapist. Three profiles were found therefore you have the problem of working out where the rapists semen got to if you suppose that JH wasn't the rapist and his DNA was introduced as a contaminant.

You are making the same mistake of logic that was made at the appeal. You are taking the result of the DNA test and then working backward to make it fit your expectations. Forget magically disappearing DNA. The issue of why only three profiles were detected is a question that has to be answered further down the line. To state that only semen could be the source of contamination is absurd and is a convenient assumption to limit the possible mechanism by which contamination could have occurred. If you cannot accept that contamination does not have to be semen then there is no point in continuing this discussion.

To use words like "bullied" you are pre-supposing that JH is innocent and have closed your mind to the possibility that he was the rapist.

Dr Evison being bullied into seeming to agree that the contaminant had to be semen has nothing to do with me pre-supposing that JH is innocent. I don't pre-suppose anything; I am simply taking a fresh look at the rationale that was used to determine that the DNA was conclusive. To that end I am not convinced but that does not mean that I have a closed mind. I could accuse you of exactly the same thing as you appear to be locked into the belief that the judgment is beyond criticism.

[JamesDean]

Hi Victor,

I agree with you that certain observations made on this thread about the appeal judgement give the definite impression of coming from a position of believing that Hanratty was innocent, and therefore believing that the DNA evidence was not only inconclusive or unreliable, and should not have been admissible - it must actually have been wrong.

Sorry Caz but I don't follow that argument at all. It's just as true to say:

I agree with you that certain observations made on this thread about the appeal judgement give the definite impression of coming from a position of believing that Hanratty was guilty, and therefore believing that the DNA evidence was not only conclusive or reliable, and should have been admissible - it must actually have been correct.

[JamesDean]

Is there any suggestion that sperm heads were looked for or found on the A6 knicker fragment? If none were found, should they have been? Or would the additional 15 years in this case have provided a reasonable explanation?

Hi Caz

If there were no sperm heads present on the fragment then there would be no DNA detected from sperm in the semen stains. It would not be possible, however, to identify individual sperm heads visually as belonging to different men; that can only be achieved by analysing the various DNA present on the fragment, some of which may not have come specifically from sperm.

I don't have any comments to make on other cases as I'm not familiar with them. However, that does not imply that I have any issue with the value of DNA analysis per se. Each case has to be taken on its own merits and I'm only looking at the A6 case.

Regards
James

[Victor]

You are making the same mistake of logic that was made at the appeal. You are taking the result of the DNA test and then working backward to make it fit your expectations. Forget magically disappearing DNA. The issue of why only three profiles were detected is a question that has to be answered further down the line. To state that only semen could be the source of contamination is absurd and is a convenient assumption to limit the possible mechanism by which contamination could have occurred. If you cannot accept that contamination does not have to be semen then there is no point in continuing this discussion.

Absolutely not. I'm working forwards from the available sample and working out what I would expect to find. You don't even have to know the results of the test to do this bit. To prove this answer this one simple question:-

What DNA do you expect to find on that knicker fragment?

After that you can compare what you expect to find with what was actually found.

Dr Evison being bullied into seeming to agree that the contaminant had to be semen has nothing to do with me pre-supposing that JH is innocent. I don't pre-suppose anything; I am simply taking a fresh look at the rationale that was used to determine that the DNA was conclusive. To that end I am not convinced but that does not mean that I have a closed mind. I could accuse you of exactly the same thing as you appear to be locked into the belief that the judgment is beyond criticism.

Can you explain then why you are interpretting the judgement as "Dr Evison was bullied" rather than "Dr Evison was convinced by the reasoned argument of the prosecution"?

[JamesDean]

Absolutely not. I'm working forwards from the available sample and working out what I would expect to find. You don't even have to know the results of the test to do this bit. To prove this answer this one simple question:-

What DNA do you expect to find on that knicker fragment?

It's irrelevant what you expect to find on any exhibit. Having expectations significantly increases the likelihood of misinterpretation. It's a well known phenomena that people tend to see what they expect to see.

Can you explain then why you are interpretting the judgement as "Dr Evison was bullied" rather than "Dr Evison was convinced by the reasoned argument of the prosecution"?

If Dr Evison was convinced then I'm sure the judgment would have said that.

[Victor]

It's irrelevant what you expect to find on any exhibit. Having expectations significantly increases the likelihood of misinterpretation. It's a well known phenomena that people tend to see what they expect to see.

No it isn't. It is vital. Every schoolchild is taught in science that you first work out what you expect to find, and then to compare what you expect to get with what you actually get, and in most cases give a %age yield.

In this case you expect to find DNA profiles from VS, the rapist, possibly MG and maybe some of the investigators\technicians and other contaminants (including JH).

What was found was VS, MG and JH. And from there you draw the conclusions.

If Dr Evison was convinced then I'm sure the judgment would have said that.

Fair enough, I should have used the words "mostly persuaded" instead of convinced, hence "he seemed to accept" with the unwritten "with some reservations" because his reservations were detailed previously.

[Victor]

I agree with you that certain observations made on this thread about the appeal judgement give the definite impression of coming from a position of believing that Hanratty was guilty, and therefore believing that the DNA evidence was not only conclusive or reliable, and should have been admissible - it must actually have been correct.

At least this doesn't include me!

I started out believing JH was innocent and the DNA evidence persuaded me otherwise, which is where a lot of other people such as Graham started too.

[Victor]

Hi James, Victor, All,

I’d be interested in hearing your thoughts regarding the DNA evidence used to convict Ronald Castree of the 1975 murder of Lesley Molseed. There appear to be one or two parallels with the DNA evidence in the A6 case.

In the Real Crime documentary shown on ITV last night it was claimed that just one bit of forensic evidence from 1975 had survived, in the form of an envelope containing a small piece of tape used on an item of Lesley’s clothing to pick up any fibres etc that may have been left by her killer. Because semen had been found on her knickers, it was thought there might just be a chance that some had been lifted up onto the surviving tape, which could provide the killer's DNA profile. According to the documentary it was the first time a DNA profile had been obtained in this way. The case was 25 years old in 2000, and was described as the oldest ever worked on at the time (?). They also had only one shot at it because the tape would be destroyed in the process.

In the event they struck lucky and discovered sperm heads in the extracted material and obtained the vital DNA profile. But no match was found in the data base and their work was kept secret so as not to alert the killer. The final breakthrough came in 2005, when Ronald Castree was accused of rape by a prostitute. A routine DNA swab gave them the match they had been waiting for and he is now serving life.

Is there any suggestion that sperm heads were looked for or found on the A6 knicker fragment? If none were found, should they have been? Or would the additional 15 years in this case have provided a reasonable explanation?

And crucially, does anyone have any doubts about the process leading to Castree being positively identified as Lesley Molseed's killer from that little piece of tape? No potential flaws in the DNA technique? The findings perfectly valid?

Love,

Caz
X

Hi Caz,

I saw the documentary last night too and was amazed at the number of similarities to the Hanratty case with regard to the DNA evidence, but there seem to be very few people jumping and shouting that Castree is innocent and the DNA was wrong.

The major point I took from the film was how appalling the treatment of Stefan was, and that the evidence that cleared him was available in 1975 and he should never have been charged.

KR,
Vic.

[JamesDean]

At least this doesn't include me!

I started out believing JH was innocent and the DNA evidence persuaded me otherwise, which is where a lot of other people such as Graham started too.

Tut tut! You are attributing that quote to me and it is simply a reversal of what Caz said.