Searching for blood, the second check and the risks to future cold cases

Its been a long while since I last posted to the blog.  The closure of the Forensic Science Service has had the effect of paralysing debate on forensic science generally here in the UK to the point where it was difficult to make a contribution regarding anything else.  Now that the FSS has closed and things are starting to settle down a little in the market, it is time to start discussing forensic science again.  As Chief Scientist for Contact Traces, an ISO 17025 accredited laboratory, I have a keen professional interest in issues surrounding  forensic quality.  I am not an expert in any kind of area associated with forensic biology and make no comment as to the effectiveness of blood searching or the likelihood of false negatives. I have been an expert in several high profile cases (including Damilola Taylor and Stephen Lawrence) where the issue over missed blood has arisen, and have witnessed at first hand how they have been dealt with by both the prosecution and defence advocates, and the experts instructed by them.

 In the case of Damilola Taylor, the failure to find blood by scientists from the FSS resulted in a government enquiry into the processes used to search for blood by forensic scientists. The enquiry held that:

Our conclusions (which are without hesitation or qualification), based upon documentary evidence and oral testimony, are that there was no systemic failure in the operations of the FSS; there were however human failures in implementing the operating procedures of the FSS which brought about the failure to recover crucial evidence; that evidence was Damilola’s blood on the right trainer (APR 60) said to belong to Danny Preddie and Damilola’s blood on a black “Giorgio” sweatshirt (APR 34) said to belong to Rickie Preddie.

and later that:

...no scientist however experienced or skilled can ever be guaranteed to find the evidence sought. Searching with the naked eye, with appropriate lighting, with microscopic aids and with the application of chemicals yields the right results in nearly all cases. But sometimes, due to human fallibility, there is failure. We do not believe that the failure rate is high; the FSS on the evidence will tolerate no acceptable failure rate and nor will any of the other Forensic Providers.

Whilst absolving the systems as error free, but the process not, the enquiry was content to recommend (albeit as an option) a second check:

The availability of a complete second scientific examination of an article should be considered as an option...

So the Damilola Taylor enquiry comes to an end recommending that if an item is found to be negative for blood that is should be searched completely a second time.  Laboratories were not obliged to do this, but some did take it upon themselves to introduce such a second check, although it was left to their discretion as to who should do it, when it should be done, how it should be done and to what extent it should be done.

Whilst the Damilola Taylor case was concluding the government were busy implementing the key recommendation from the 1999 Mac Pherson enquiry into the case of Stephen Lawerence, that to change the law so as to allow suspects previously tried and acquitted, to potentially face a re-trial if new evidence met a legal threshold.  This was made a statutory reality in Section 76 of the Criminal Justice Act 2003, which required that the CPS can seek a retrial for a suspect determined by a hearing at the court of appeal.  The CPS would be successful if they could prove that the evidence was new, compelling and if a re-trial was in the public interest.

One of the first cases to test the new law was the murder of Vikki Thompson.  Mark Weston was acquitted of the murder in 1996, however new examinations had revealed the presence of blood on a pair of his boots that yielded a DNA profile matching that of the victim.  In echoes of the Damilola Taylor case, the court of appeal had to consider why the blood was missed the first time around, and crucially what the role of the forensic scientists was in this process and whether or not they were negligent in missing the blood.

The court held that:

...Although there have been very substantial advances in DNA science in the period from 1995 to the present, particularly in the improvement and validation of more advanced profiling, the basic techniques for detecting blood on surfaces such as boots have not materially changed.  The search is still made using the naked eye and/or a microscope and the surface is rubbed with filter paper as part of the KM test or similar tests.

Further:

...we accept, that the examination of dark coloured boots for blood is in itself a difficult task.  Furthermore, not only is the surface uneven, but it is difficult to examine them under a microscope.  Because of these difficulties it is possible for a competent examiner not to find visible traces of blood.

The court of appeal has just come to the conclusion that there exists systemic error in the searching for blood, if perhaps only in a system for searching whereby a human being searches an item for blood  (at least for items such as dark coloured boots), because they expect errors to arise when even a competent examiner performs the search.

Similarly in this case the issue over checking arose:

...The areas examined by Mr Mann in 1995 were not checked by Ms Miller in 1996 and the examination by Ms Miller in 1996 was not checked on its completion by Mr Mann.  At that time it was not sufficiently appreciated that a second check was necessary. 

The court appeared to believe that the recommendations of the Damilola Taylor enquiry have been implemented because the judges go on to state:

...two examinations are now required, though there must remain the risk that even two will not detect all the blood.  Again it seems that another explanation as to why the blood might have been present but not detected was the failure to conduct two examinations of the same areas in 1995/6.

The court turned to consider the diligence of the forensic scientists in 1995/6 and they said:

...the powerful point was made on behalf of the respondent that whereas missing one area of blood might be explicable, missing at least four areas of blood was not consistent with a careful and diligent inspection.

Crucially the court took notice of the difference in the way the blood search was undertaken, and it appears that it is this point, and this point alone, which enabled the court to clear the FSS scientists of any allegation that they had acted without due diligence:

Without the evidence of the change in practice and without the evidence of Ms Rosalyn Hammond and Ms Caroline Hughes, this would have been a very powerful submission.  Ms Hammond and Ms Hughes agreed that blood stains can be missed on items such as boots, even when they have been examined by careful and diligent forensic scientists.  However it seems to us in the light of that evidence, although we remained concerned about the circumstances of the original examination of the boots, it would be wrong for us to conclude that either Mr Mann or Ms Miller had acted without due diligence.  It is clear that some criticism should attach to the FSS in not providing proper and up-to-date lighting in 1995/96, but again it does not seem to us that on its own we could say that that amounted to a failure of due diligence on the part of the FSS itself.

In clarifying this point the court stated that:

At the time of the investigation in 1995/6, as we have set out at paragraph 37v) above, there was insufficient understanding of the fallibility of testing for blood and the necessity of a second and thorough check.  Were it not for that lack of understanding, the question would have arisen (though we need not decide it) as to whether it is in the interests of justice, where an investigation is concluded and a matter brought to trial on the basis of scientific tests known to be fallible, that the powers under Part 10 of the 2003 Act can be used to re-open an investigation.  We will merely observe that it is plainly in the interests of justice that there is an end to litigation. 

and crucially, in relation to possible future applications to re-prosecute with new evidence:

Where a test is known to be fallible, every effort must be made to ensure accuracy; reliance should not be placed on the possibility of trying again under Part 10.a

The court has stated clearly here that the traditional process for searching for blood is now known to be fallible, because the scientists have stated so.  This, according to Tim Roberts QC, could have serious implications:

The reason for the abolition of the double jeopardy principle was to preserve respect for the Justice system after the anticipated advance of science had made a mockery of past verdicts based upon inferior forensic scientific techniques.

 However, once it is known that a particular test is ineffective, it will not do in future to use it, fail to secure a conviction, and later hope to make a section 76 application when you have more time and resources to do the job properly. This should mean that, from now on, mere KM testing for blood and only primary transfer, external garment evaluation of fibre evidence, if it results in an acquittal, should operate to defeat any future section 76 application based upon a later more thorough examination.

 The point I derive from this is that, now that well informed scientists must know that KM testing for blood, however many times it is carried out and however many scientists carry it out, is not going to reveal blood deposits up to 0.5mm x 0.3mm in dimension, it will henceforth be negligent to fail to carry out LPM [Low Power Microscopy] scrutiny of the garment.  If a later cold case review utilises LPM examination of a garment and finds blood, an application to quash an acquittal and retry an accused on the fresh findings should fail.

Looking back at the Damilola Taylor case, it is arguable that at least in the case of the blood stain on the trainer which was visible by the naked eye, that if Danny Preddie or Ricky Preddie had been tried in the first trial and acquitted, that an application to quash the acquittal, seeking a retrial on the basis that the blood stain was new evidence would fail because of a lack of diligence on behalf of the scientists in the original investigation. 

But what of the second check?  If a second check takes place, as recommended by the enquiry and is found to agree with the first examination does that mean we can be confident that there is no blood on the item?  The recent findings in the Stephen Lawrence case give us serious concern as to the effectiveness of such an approach. In the Stephen Lawrence case, a jacket LH/5 was examined 6 times by six different scientists from four different organisations, over a period between 1993 and 2008 and the result was always the same no blood. A fibre was found on the jacket, indistinguishable from a garment worn by Stephen Lawrence which appeared to have a component that could be blood in its MSP spectrum.  It was only after this fibre was found was the jacket was examined again, re-searched using LPM for a seventh and then eighth time, when blood was found on the jacket, including a stain on the collar.   It is arguable that without the fibre evidence, the blood would not have been found.

Einstein is credited as saying that the definition of insanity is to repeat the same experiment over and over and to expect different results.  Second, third, fourth and so on checks where the check is precisely the same process as the first examination appears to fall into that category, at least where the searching for blood is concerned.  However, checks where the search is undertaken using a different process, such as LPM, or perhaps some other technique that does not rely so much on the human eye appear to be the way forward. 

The fact though that so many scientists from so many laboratories failed to find the blood, even as recently as 2008, and that scientists accept the fallibility of the processes, raises the question as to how many cold cases remain cold cases because blood has been missed. Furthermore that the court of appeal has stated that it is willing to consider that the direct actions of the scientists amount to a lack of diligence which could lead to the failure of applications under double jeopardy -even if new evidence was found. Ironically, the key to the outcome of such applications may not be the new evidence at all, but the manner in which it was found. 

The role of the Senior Scientist in Forensic Science in the UK today

Over the years a succession of successful cold case reviews have seen police and forensic scientists working at close quarters with each other to a different level than usually seen in 'live' cases. The experiences of the police in conducting these reviews at the laboratory level with scientists has put the spotlight onto the roles of the senior scientist, the laboratory practitioners and the investigators themselves. The success of these cold cases appears to have been some kind of pyrrhic victory for the senior scientists, successfully solving cold cases at the cost of showing the police how to do it.

A question often posed by those seeking to understand issues that have arisen in past cases so as to improve current and future practices is whether the setting of forensic strategy and the prioritization of exhibit examinations requires a skill that only senior forensic scientists possess? What by way of scientific knowledge makes a scientist more effective at this process than anyone else (such as an investigator for instance) and what precise scientific method are we using to determine which exhibits we should examine, for what and in what order? If the answer is that we read the case circumstances provided by the police, roll the dice and take our chances that is arguably no more scientific than the police sending in items and asking the lab to 'forensicate' the case.

The police, it would appear, have made up their own mind. In most forces the role of deciding forensic strategy and exhibit prioritization rests with scientific support functions internally. That is not to say that the police do not seek scientific advice from the forensic scientists regarding strategy etc, of course they do and in my experience, they more often than not seek out advice so as to make an informed choice. But it is a fair reflection of the status quo in the UK to say that it is the police who ultimately decide on the strategy and priority of exhibit examinations, and they do so whilst working under budgetary constraints.

Other forces have taken it to another level entirely, performing the strategy setting and prioritization functions of the senior scientists themselves - whether by employing scientists or utilizing other in-house functions, but also employing laboratory level practitioners to process exhibits - only really drawing the line at performing the analysis of samples (such as DNA etc) themselves. The economic argument for them doing so in-house, rather than utilizing the established external forensic provider market has not been published. Given the costs of not only employing scientific staff but also investing in facilities and the costs of gaining accreditation, it is doubtful that the economic argument will turnout to be persuasive for in-force provision compared to seeking a competitive rate in the external market - at least in the short term, but that would be largely missing the point. The point is that some of the police forces have seen how complex casework is done and they believe that they can do at least as good a job themselves in-house and that appears to be enough for them to consider that in-force provision is the way forward.

Whatever happens in the future, the market paints a bleak picture for the future role of the senior scientist.

Validation, Validation, Validation - what now for forensic R&D?

In the wake of recent court judgements (R-v-Hoey and the subsequent enquiry, followed by the judgement in R-v-Reed) and the publication of the Regulator's draft codes of conduct which attempts to define validation, the issue over whether or not a technique / process has been validated continues to cause utter confusion.

In R-v-Hoey the issue over whether or not the process used by the FSS in dealing with low-template DNA analysis (LCN or "Low Copy Number" as used by the FSS) was scrutinised comprehensively, and challenged by the defence team on the basis that it was not a valid process.

The FSS stated that they had put LCN through their own validation processes including the publication of the method in peer reviewed journals. Furthermore the FSS had been through several rounds of accreditation (inspected by UKAS) during which the process of LCN would have been explored in detail.

The court held that this was not enough and ruled that:

"...However, in the case of LCN there is no validation other than the assertion by Drs Gill and Whitaker that two published journal papers they had written amounted in effect to peer review and thereby the necessary validation, a proposition which was strongly disputed by the Defence experts..."

A government enquiry - held in the aftermath of the judgement held that:

"...we find that the science supporting the delivery of Low Template DNA (LTDNA) analysis is sound and that the three companies (the Forensic Science Service Ltd, LGC Forensics and Orchid Cellmark Ltd) providing this service to the Criminal Justice System have validated their processes in accord with accepted scientific principles using both 28 and 34 PCR cycles for extracts containing less than 200 picograms (pg) of DNA."

In R-v-Reed the court went further and stated that:

"...On the evidence before us, we consider we can express our opinion that it is clear that, on the present state of scientific development:

i) Low Template DNA can be used to obtain profiles capable of reliable interpretation if the quantity of DNA that can be analysed is above the stochastic threshold – that is to say where the profile is unlikely to suffer from stochastic effects (such as allelic drop out mentioned at paragraph 48) which prevent proper interpretation of the alleles.

ii) There is no agreement among scientists as to the precise line where the stochastic threshold should be drawn, but it is between 100 and 200 picograms.

iii) Above that range, the LCN process used by the FSS can produce electrophoretograms which are capable of reliable interpretation. There may, of course, be differences between the experts on the interpretation... However a challenge to the validity of the method of analysing Low Template DNA by the LCN process should no longer be permitted at trials where the quantity of DNA analysed is above the stochastic threshold of 100-200 picograms in the absence of new scientific evidence..."

So at the end of an internal validation by the supplier, several rounds of UKAS accreditation and inspections of the supplier during which the technique was in use, two appeals and a government enquiry, it is the appeal court which drew a line at above 200 picograms here - not the scientists, and not the government.

So how exactly can a method or process used in forensic science be deemed valid? Internal process do not seem to be enough, nor does publication in a peer reviewed journal, nor does an accreditation of the system (of which the process is a part) to a national standard and nor does an independent review of the science by the government suffice. Right now, it is the court that is deciding whether or not a process is valid and furthermore it is defining the analytical levels at which that validity can be challenged.

The regulator demands that providers be accredited to ISO17025 (to be replaced by the forensic standard in due course). Either way, these standards demand validation of processes. UKAS require documented evidence of the technique used in casework so that they can grant accreditation. So in order to bring in new science to forensic science, the supplier must bear the risk of introducing it to casework without it being assessed against the standard in the first place.

Commerical forensic science providers now have to weigh up the probability that their R&D would survive a challenge in court - and if the R&D failed, what the impact on their business might be. It is not just the money that is invested in R&D, it is not just the business that you might win on the basis of the new R&D, it is also the business that might be lost if the court rules against it and/or limits its use or scope. For some suppliers that might be cause enough to close down any R&D programmes that still exist - and who could blame them for that?

Now is not a good time to be doing R&D in forensic science in the UK.

The Bayesian Approach - How are we Doing?

Much has been written about how Bayesian interpretation can be applied to different evidence types over the last fifteen years, and lately there have been attempts to adopt the approach right the way through the forensic process, in some cases even starting before items are submitted, and in other cases ending with the scientist making up a defence scenario on behalf of the defendant.

Here in the UK, the Forensic Regulator has recommended that accreditation to 17025 (and further to a new forensic standard to be published in due course) is the only standard that forensic laboratories need. The Forensic Regulator was also of the view that individual practitioners employed by organisations who hold the standard do not need anything further, as merely by virtue of their employers status as an accredited laboratory this ensures their competence.

Part of the 17025 standard requirement is for proficiency testing to occur on a regular basis. If the test is externally administered it is considered to be an excellent means of evaluating the performance of a laboratory and by implication it is a measure of the laboratory systems and the competence of its staff.

There are very few commercial providers of forensic proficiency testing in trace evidence in the world. The oldest and most accepted is CTS in the US. They produce and administer proficiency tests over a wide range of evidence types every year. A report on each test is produced and published, the identities of the laboratories are kept anonymous by means of assigning each lab a unique code.

The CTS fibre proficiency test tends to follow a set format that tests the laboratory's ability to identify and compare fibres from three samples. For this part of the test there are three possible outcomes either the samples match, don't match, or the findings are inconclusive. In reality, for laboratories undergoing the test there are only two outcomes - either you get it right or you get it wrong. Get it right and the lab's systems are deemed in good working order, and its staff are deemed competent (at least those who took the test anyway), get it wrong and the accredited lab has to investigate and take action according to their process. Getting it wrong is as serious an issue as it gets for an accredited lab and its staff.

The second part of the test is of general interest but does not count as a proficiency in real terms because there is no expected outcome. The participant lists the techniques used and their conclusions. There is no right or wrong answer for these and the participants are under no obligation to enter any data at all here.

This year's report on the fibre proficiency test 10-539 has just been published. As all accredited laboratories in the UK are likely to have performed this test, and how all are likely to have used the Bayesian approach, the publication of the report provides an opportunity for an assessment of how labs interpret fibre evidence in this way. Each lab appears to have got the same (correct) scientific result with respect to the matching fibres and all were given precisely the same information.

The scenario given was straight forward, a sample from the inner lining of a jacket, and two clumps of fibres, one found on the inner door latch on the passenger side of a truck, the other on the driver's seat of the truck. After testing, only the clump on the inner door latch was found to be indistinguishable from the lining of the jacket.

Here's the conclusions that had Bayesian elements from this year's test, they can't all be right, you can decide which approach you like best:
Lab 1

Door latch on the passenger side of the suspect's truck: Orange polyester fibres (item 2) of two types, indistinguishable from the two types of polyester fibres used in construction of the jacket lining (item 1),were found on the inner door latch on the passenger side of the suspect's truck. In interpreting the scientific findings I have considered two alternative propositions: The jacket lining (item 1) had been in contact with the inner door latch on the passenger side of the suspect's truck. The jacket lining (item 1) had not been in contact with the inner door latch on the passenger side of the suspect's truck and the polyester fibres originated from another item(s) constructed of the same two types of indistinguishable orange polyester fibres. In my opinion, the scientific findings provide strong scientific support for the former proposition rather than the latter. In expressing the evidential significance of my findings, I have used the following scale: no scientific support, limited, moderate, moderately strong, strong, very strong and extremely strong scientific support. Driver's seat of the suspect's truck: In my opinion, the fibres (item 3) recovered from the driver's seat of the suspect's truck did not originate from the lining of the jacket (item 1).

Lab 2

I have considered the following propositions for the finding of the orange polyester fibres of two types (item 2) indistinguishable from the two types of polyester fibres that comprised the lining of the victim's jacket (item 1) on the inner door latch of the passenger side of the suspect's truck: The victim had been inside the vehicle and fibres were transferred from the victim's jacket to the door latch. The victim had not been inside the vehicle and the fibres found originated from another item(s) composed of the same two types of indistinguishable fibres. In my opinion, the findings provide strong scientific support for the former proposition rather than the latter. In my opinion, the fibres recovered from the driver's seat (item3) did not originate from the lining of the victim's jacket.

Lab 3

These findings provide very strong support for the suggestion that the fibres from the inner door latch on the passenger's side of the suspect's truck came from the inner lining of the victim's jacket. These findings show that the fibres from the driver's seat of the suspect's truck did not come from the inner lining of the victim's jacket. I have chosen the above phrases from the following scale; weak support, moderate support, moderately strong support, strong support, very strong support and extremely strong support. The conclusion was addressed at source level due to the limited samples received. In a case situation the jacket and further samples from the truck would have been available, in which case the activity level
could have been addressed.

Lab 4

The orange polyester fibres of Item 2 were indistinguishable in terms of their microscopical appearance and colour from the orange polyester fibres used in the construction of Item 1. In assessing the laboratory findings and drawing my conclusions, I have considered the following two alternative propositions: The fibres recovered from the inner door latch of the passenger side of the truck, Item 2, originated from the inner lining of the jacket, Item 1. The fibres recovered from the inner door latch of the passenger side of the truck, Item 2, did not originate from the inner lining of the jacket, Item 1. In my opinion, the laboratory findings are more likely if the first proposition were true rather than the second alternative. In my opinion, the laboratory findings provide very strong scientific support for the proposition that the fibres recovered from the inner door latch of the passenger side of the truck, Item 2, originated from the inner lining of the jacket, Item 1.

Lab 5

Sixteen fibres from the driver's seat (Item 3) was recovered for examination by comparison microscopy. No fibres matched the component fibres of the jacket inner lining (Item 1). Sixteen fibres from the inner door latch (Item 2) were recovered for examination by comparison microscopy. A sample of these fibres were further analysed by microspectrophotometry and infrared spectroscopy. All were indistinguishable from the component fibres of the jacket inner lining. These findings would support the proposition that there had been direct contact between the inner door latch and the lining of the jacket.

Lab 6

In our opinion, orange polyester fibres from a yarn recovered from the passenger side inner door latch of the suspect's truck (Item 2), correspond to the orange polyester fibres of the victim's inner jacket lining. In addition, the presence of the orange polyester fibres in the form of a yarn, in our opinion, means that it must have been shed from a damaged garment, such as the victim's jacket. In assessing the evidential significance of these findings, we have considered two possible explanations for the matching fibres: (1) The yarn of orange polyester fibres from the passenger side inner door latch of the suspect's truck, is from the inner lining of the victim's jacket; Or, (2) The yarn of orange polyester fibres from the passenger side door latch of the suspect's truck is NOT from the inner lining of the victim's jacket, but originates from another damaged garment that sheds yarns that happen to match the orange polyester fibres of the jacket lining by coincidence. In our opinion, the orange polyester fibres of two types found on the passenger side door latch of the suspect's truck are relatively uncommon. The presence of these two fibre types matching the inner lining of the victim's jacket in our opinion provides greater evidence of a link between the victim's jacket and the passenger side inner door latch of the suspect's truck, than would have been the case with an apparent transfer of a single fibre type alone. Therefore in our view this makes the first explanation for the findings far more likely than the second. In our opinion, the fibre transfer evidence therefore provides strong scientific evidence of a link between the victim's jacket and the inner door latch on the passenger side of the suspect's car. No fibres matching the component fibres of the victim's jacket lining were found within Item 3.

Lab 7

The findings in this case, and the information provided, have been used to address the following propositions: a) The damaged lining of the victim's jacket has been in contact with the inner door latch of the suspect's vehicle. b) Some other item left the fibres on the inner door latch of the suspect's vehicle and any matching fibres recovered are due to chance. Taking the results of the examinations in this case together with published studies and casework experience, in my opinion, the likelihood of finding two distinct fibre types of an orange colour randomly in the population is fairly low. In addition, given that these fibres would shed only due to the lining being damaged, that there are two distinctly different fibres comprising the warp and weft of the fabric, and that both of these fibre types were recovered from the inner door latch and are found to be indistinguishable in terms of colour, dye and chemical composition, to the polyester fibres of the warp and weft of the jacket lining then, in my opinion, there is very strong support for the view that the damaged lining of the victim's jacket has been in contact with the inner door latch of the suspect's vehicle rather than the fibres transferred originating from some other item by chance. The term "very strong support" is selected from a scale of standard terms used to express the relative level of scientific support for a proposition over its alternative, as discussed above. These terms are: Limited, Moderate, Moderately Strong, Strong, Very Strong, Extremely strong Additionally, in some instances, a proposition may be conclusively supported, if the findings are such that the alternative can be dismissed. If the findings provide no greater support for one proposition over the other, then the findings are described as inconclusive. My interpretations and conclusions are based on the background information available to me at present. If any of this information changes, or is found to be incorrect, then I may need to reassess my findings.

Lab 8

Item 1 comprised a square of orange fabric with one glossy side and one matte side. The fabric was composed of orange, delustered, polyester warp fibres with hexagonal cross section and orange, non-delustered, trilobal polyester weft fibres woven together to form a 2:1 twill. Item 2 comprised orange, delustered, polyester fibres with hexagonal cross section. These fibres corresponded in appearance, composition and colour with fibres from the warp threads in Item 1. The results support the proposition that the fibres recovered from the inner door latch on the passenger side of the suspect's truck shared a common origin with the known section of fabric from the inner lining of the victim's jacket (Item 1). Item 3 comprised orange, multilobal acetate fibres. These fibres differed in appearance, composition and colour with the fibres from Item 1. The results do not support the proposition that the fibres recovered from the driver's seat of the suspect's truck shared a common origin with the known section of fabric from the inner lining of the victim's jacket (Item 1)

Lab 9

The sample from the victim's jacket (item 1) contained two types of orange polyester fibres. The sample from the inner door latch of the suspect's truck (item 2) contained two types of orange polyester fibres. These fibres could not be distinguished from the fibres from the victim's jacket (item 1) by microscopy, colour comparison and infrared spectroscopy. The sample from the driver's seat of the suspect's truck (item 3) contained orange acetate fibres. These fibres were different to the fibres of the victim's jacket (item 1) and therefore are not from the victim's jacket. In my opinion the scientific evidence strongly supports the proposition that the fibres from the inner door latch of the suspect's truck (item 2) are from the victim's jacket (item 1). I have chosen the term "strongly supports" used in describing the scientific evidence above from the following scale of terms: inconclusive, slightly supports, supports, strongly supports, very strongly supports and conclusive.

Lab 10

The forensic significance of fibres is partly dependant on the number of fibres present, and how common that fibre type and/or colour is in textile manufacturing. The fabric in Item #1 was constructed from two different types of orange polyester fibre. The orange polyester fibres from Item #2 were indistinguishable from one type of the fibres in Item #1. The number, colour and length of the fibres present strongly supports the hypothesis that the fibres in Item #2 originated from the same source as Item #1. The fibres in Item #3 were different to those from Item #1 and, as such, could not have originated from the same source.

Lab 11

Based on visual, chemical and colour analysis the two types of orange polyester fibres recovered from the inner door latch on the passenger's side of the suspect's truck (item 2) could have come from the inner lining of the victim's jacket (as represented by item 1), or from a textile containing fibres with the same visual, chemical and colour features. Based on visual, chemical and colour analysis the fibres recovered from the driver's seat of the suspect's truck (item 3) could not have come from the inner lining of the victim's jacket (as represented by item 1). In my opinion, this fibre evidence supports the proposition that the inner lining of the victim's jacket (item 1) came into contact, either directly or indirectly, with the door latch on the passenger's side of the suspect's truck. Note that as fibres are mass produced another source of fibres with the same visual, chemical and colour is possible.

Some use two propositions, some using one, some using scales of support some not. Some attach a very strong level, others a strong level, others no level at all. Some place the victim inside the vehicle, others include the possibility of indirect transfer. Some used different scales. Some believe that the scientific findings can be used to show support for the fibres coming from the victim's jacket rather than any other item made of fibres indistinguishable to it, others believe that the scientific findings can be used to show support for the fibres coming from the victim's jacket rather than via contact with any other item by chance. These are not the same propositions.

But what is clear is that given the same scenario and the same results, that the approach to Bayesian interpretation of fibre evidence varies widely from one laboratory to another, and by implication, one scientist to another. These issues are not unique to fibre evidence. Using Bayesian interpretation as a standard approach in this way does provide a common language for us as forensic scientists to communicate our findings. We just don't seem to be very good at it. It would appear that the common language does more to separate us than unite us.

Is it a matter of competence of the individual, the system of peer review, or a cultural approach by the laboratory? Either way, current quality systems do not address it. But perhaps this is where the regulatory line should be drawn, and that the courts, not the regulatory bodies, are better placed to test matters of individual opinion, after all it is the individual scientist, not the organisation that employs him that is on the stand.

The end of an era: Ken Wiggins and Mike Grieve

It was with great sadness that 2009 marked the passing of Ken Wiggins. Together with Mike Grieve (who passed away in 2002), they will be sorely missed by all who knew them.

Ken and Mike were very well known in the global Forensic Fibre community. Pioneers in the field of fibres, the numerous papers they published on the topic of forensic fibre examination will be a legacy that will endure. However, perhaps their greatest contribution to forensic science was in their partnership with the foundation of the European Fibre Group (EFG), a group Ken was to lead as president (until he retired in 2006).

History can sometimes reduce the impact of an individual to a chronology of milestones but as always its the stuff inbetween that really matters. Ken and Mike were professional at all times and they shared a vision for the EFG that carried the group forward. The emphasis on Research and case studies that formed the basis of the EFG meetings pre and post ENFSI, made the group distinctive and served to raise the standard of forensic fibre work via a combination of education and encouragement. This was largely down to the tone set by Ken and Mike. They worked hard, and worked the group hard, but they could let their hair down afterwards and compete with each other the next morning as to who could look the least hungover. Together they achieved a lot, and both will be missed by all who knew them.

A new era for Forensic Fibre Examination is beginning in the backdrop of emerging new EU regulations in Forensic Science and emerging markets. It will be interesting to observe how well the EFG will adapt to the new challenges ahead.

Spectroscopic analysis of body fluids - update

Raman spectroscopic signature of semen and its potential application to forensic body fluid identification, this paper was recently published in FSI and is an update on the ones from last year (Raman spectroscopy offers great potential for the nondestructive confirmatory identification of body fluids and Analysis of body fluids for forensic purposes: From laboratory testing to non-destructive rapid confirmatory identification at a crime scene). This study, more indepth than the previous ones and focussing on semen, identified three key indicating components of interest from a raman spectrum that can be used to identify a semen sample. However, there were several contributing species (shown in the spectrum below) that made up the three components namely:

Tyrosine (peaks in green)
Albumin (peaks in blue)
Choline (peak in yellow)
Spermine phosphate hexahydrate (peaks in purple)

The potential for being able to identify dried semen on tapings using a confocal approach, would appear to be possible, particularly useful for old (cold) cases where the items of clothing may no longer be available.

One slight concern was the strength of the laser used to obtain the data in the paper. 115mW seems like a lot for a biological sample which you would not wish to heat. No attempt was made to assess the impact of the technique on any DNA process after analysis so its not a validation of the process for forensic use, but its a step in the right direction.

Fibre papers published 2009

There were several papers published in 2009 on fibres. Some of these are considered below in no particular order.

The population, transfer and persistence of fibres on the skin of living subjects was published in Science and Justice. Papers that deal with the difficult issue of fibre persistence are always of great interest because of the complexities involved in the subject. This paper did a good job of converting theoretical knowledge of fibre transfer and persistence into casework situations involving exposed skin and provided a scientific basis for assessing fibre populations on skin. Scene-going scientists would benefit from understanding the data as it would assist in their evaluations of the potential for fibre recovery.


The kinetics of colour change in textiles and fibres treated with detergent solutions: Part I—Colour perception and fluorescence microscopy analysis and The kinetics of colour change in textiles and fibres treated with detergent solutions: Part II — Spectrophotometric measurements both published in S&J. Fibres that have been washed could theoretically appear different under the microscope owing to the contribution from the detergent. This not only could affect items of clothing submitted as reference samples (so that the reference sample is different from any at the scene), but populations of fibres on clothing (so that any potentially linking recovered fibres appear to be different). These papers describe in detail the types of changes that could occur for several different fibre types at the microscopic and chemical levels. The papers serve as good background information and as a reminder to fibre examiners to question and challenge what they see down the microscope.

Automotive flock and its significance in forensic fibre examinations this was one of our papers and was a study that came directly from our casework experiences.

The application of laser scanning confocal microscopy to the examination of hairs and textile fibers: An initial investigation this paper, from Forensic Science International, showed that the LCM technique produces some excellent images of fibres in terms of their cross section and gave some valuable pointers for optimizing conditions for capture. LCM is a technique that at present is not widely available to all. The non-destructive aspect of the capture of the image is most appealing, although when compared to the cheap alternatives (such as cutting the fibre) it is a luxury.


The Analysis of Metameric Blue Fibers and Their Forensic Significance , this paper focussed on metamerism and demonstrated that even though samples are metameric - they are likely to be distinguishable via their UV-VIS-NIR spectra. This study may seem obvious, but it was an important point.