a survey of paint flakes on the clothing of persons suspected of involvement in crime
TRANSCRIPT
Science and Justice 52 (2012) 96–101
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A survey of paint flakes on the clothing of persons suspected of involvement in crime
Rachel Moore, Delia Kingsbury, Joanna Bunford, Valerie Tucker ⁎The Forensic Science Service®, 2960 Trident Court, Birmingham Business Park, Solihull Parkway, Birmingham, B37 7YN, United Kingdom
⁎ Corresponding author. Tel.: +44 121 329 5440; faxE-mail address: [email protected] (V.
1355-0306/$ – see front matter © 2011 Forensic Sciencdoi:10.1016/j.scijus.2011.08.002
a b s t r a c t
a r t i c l e i n f oArticle history:Received 11 June 2010Received in revised form 20 July 2011Accepted 4 August 2011
Keywords:PaintClothingSurvey data
A survey was undertaken to determine the background level of paint flakes on the clothing of personssuspected of involvement in crime. The debris from 100 garments submitted for casework examination wasstudied and paint flakes recovered where present. Seventy two percent of garments bore one or more flakes. Atotal of 703 flakes were recovered; size, topcoat colour, and number and colour of any under-layers wererecorded for each. The distribution of paint flakes on clothing surfaces and in pockets was also noted. Resultswere compared with the previously published survey of Pearson, May and Dabbs (1971). This survey providesscientists with an updated data set for reference when considering the strength of paint evidence.
© 2011 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction
Paint is widely encountered by forensic scientists working in thefield of trace evidence and has considerable potential as a source ofevidence. Its presence is usually governed by direct contact and itspersistence dependent on the surface area, duration and force ofcontact, amount of material transferred, the activities of the recipientafter contact and the resulting time interval until sampling.
Single layer paint samples that appear indistinguishable by colourcannotbe asserted tohave come from the same sourcewithout knowinghow common the paint is in the environment. With additional data, itmay be possible to estimate the probability of the defendant becomingexposed to an alternative source of the same paint in a restricted timeframe and small geographical area. This contextualising of analyticalresults given a set of conditions is the basis of interpretation, a skillwhich has developed from a common sense, classical methodology to amore statistically based approach with the application of Bayes'theorem. However, statistical models require data to inform them andthere are few published paint data sets.
The surveypublishedbyPearson et al. [1] reportedon thedistributionof paint and glass on clothing taken to a dry cleaning establishment. Thestudy was performed over forty years ago and the clothing examinedwas not typical of the style of garments currently submitted for forensicanalysis of particulates. Lau et al. [2] examined clothing from high schoolstudents. The frequencyof paintflakes amongst their test populationwasfound to be significantly lower than the Pearson et al. study [1]. It wassuggested that the findings might have been influenced by theenvironment; the most common type of paint recovered appeared tohave originated from the school itself. Themore recent survey by Buzzini
: +44 121 622 2051.Tucker).
e Society. Published by Elsevier Ire
et al. [3] of crowbar andhousehold paints in burglary cases addressed therange of colours likely to be encountered on crowbars, and the painttransferred between crowbar and scene as a result of forcing a paintedsurface. Their data are not comparable with the survey presented hereinas Buzzini et al. [3] did not consider the transfer of paint to clothing.
In the interpretation of paint, as with any evidence type, it isimportant to consider how likely it is that paint flakes of a certaincolour and layer sequence will be found at random on an item ofclothing. In the absence of published surveys and similar exploratorywork, the reporting scientist must rely on their own experience andability to recall what is commonly or rarely seen amongst debriscollected from garments. This paper sets out to address the lack ofcontemporary paint flake data and to provide information that can beused as guidance when scientists need to consider the relativefrequencies of paint flake size, colour and layer sequence. The surveytargets clothing of persons suspected of involvement in crime, akin tothe glass survey performed by Lambert et al. [4].
The debris from 100 garments submitted for casework examinationof other particulate types, predominantly glass, was examined after thecompletion of evidential work. The presence of paint flakes wasrecorded separately for the surface and pockets of each garment. Eachrecovered paint flakewas characterised by recording its size, colour andlayer sequence. As thepaintflakeswere recovered fromcasework items,their examination was limited to techniques that would not alter theirform, in case they became significant at a later date and required forevidential purposes.
2. Collection and processing of data
The surveywas conducted at the Forensic Science Service laboratory,Birmingham. The items from which data were collected were amongstthose submitted for examination for the presence of glass fragmentsduring 2007. The debris collected during the evidential search was
land Ltd. All rights reserved.
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Total numbers of paint flakes recovered
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Fig. 1. Percentage of garments with respect to number of paint flakes recovered. Thetotal number of paint flakes recovered from each of 100 garments was recorded. Totalnumbers were divided in to subgroups for graphical presentation.
97R. Moore et al. / Science and Justice 52 (2012) 96–101
subsequently reviewed for the presence of paint flakes using astereomicroscope (Nikon) at ×15magnification. All paint flakes greaterthan 0.1 mm were recovered, and their approximate size measuredusing amicrometerwith0.1 mmdivisions. Paintflakes less than0.1 mmin size were not recovered owing to difficulties in determining theircharacteristics. Initial colour assignation was made visually using thestereomicroscope.
High Power Microscopy examinations were carried out using anOlympus BX41 microscope and incident illumination with Dark Field,Bright Field and Fluorescence illumination — the latter in conjunctionwith blue, blue-violet, violet and UV filters.
Paint flakes were assigned a colour using the Methuen Handbook ofColour [5]. It should benoted that as a colour description encompassed anumber of shades and hue of a given colour, further colourdiscrimination could be achieved over and above that apparent fromthe assigned colours. In assessing the colour of middle layers a moregeneral description of colour was assigned as the area of paint visible forassessment was small, and no sample preparation could be undertaken.
It should be noted that all the particles recorded in this surveyappeared to be paint flakes, but as no further analysis could beperformed some of the particles may not have been paint.
3. Summary of data
3.1. Number of paint flakes on garments
A total of 703 paint flakes were recovered from 100 items. Debrisfrom theupper and lowergarments of 15 individualswas examined; theremaining 70 samples were all from garments of different individuals.
Table 1Number of paint flakes recovered from the pockets and surfaces of 85 garments. Garmentstypes and comparison of the recovery of flakes from surfaces and pockets.
Garment type Garmentsanalysed
Number with no paintflakes
Number (and %) with paintflakes
Coat/jacket 25 7 18 (72%)Tracksuit top 10 0 10 (100%)Cardigan/jumper 4 0 4 (100%)Zip up top 2 0 2 (100%)Hooded top 19 4 15 (79%)Shirt 2 1 1 (50%)T-shirt/vest top 6 4 2 (33%)Tracksuit
bottoms10 5 5 (50%)
Jeans 6 1 5 (83%)Shorts 1 1 0 (0%)
85 23 62
Debris from 84 upper garments, including jackets, jumpers,cardigans, shirts, t-shirts and gloves, of which there were eight pairs,was examined. Sixteen lower garmentswere examined, including jeans,tracksuit trousers, jogging bottoms and shorts. A large variation in thenumber of paintflakes recoveredwas observed,which did not appear tobe related to the fabric type or style of the garments.
The number of paint flakes recovered from upper body garmentscovered a range of 0–57, and the number recovered from lower bodygarments covered a range of 0–48. From the majority of garments(66%), five or less paint flakes were recovered. No paint flakes wererecovered from 28% of garments, and between one and five flakeswere recovered from 38% of garments. More than 20 paint flakes wererecovered from eight percent of garments, and just one percent hadgreater than 50 flakes (see Fig. 1).
Of the upper and lower body garments from the 15 individuals, nopaint flakes were recovered on the upper and lower clothing fromthree individuals. In six cases more paint flakes were recovered fromupper body garments, three of these cases having no paint flakes onthe lower body garment. In six cases, more paint flakes wererecovered from the lower body garments, three of these cases havingno paint flakes on the upper body garment.
3.2. Distribution of flakes on garment surfaces and in pockets
Of the 100 garments surveyed, 15 did not have pockets. Of theremaining 85 garments, 100% of the tracksuit tops, cardigans, jumpersand zip up tops examined (n=16) presented paint flakes (seeTable 1). A large percentage of coats, jackets, hooded tops and jeans(n=50) also possessed paint flakes (72–83%). In total, more paintflakes were recovered from pockets (344) compared with surfaces(223).
No paint flakes were recovered from 28 of the 100 garments, anadditional ten garments were amongst the 15 with no pockets. These38 items were excluded from the distribution analysis of 62 garmentswith pockets in Fig. 2. A greater number of paint flakeswere recoveredfrom the pockets of 29 clothing items, than from the surfaces of 31items. There were equal numbers of paint flakes recovered from thepockets and surfaces on two garments. For 20 items, paint wasrecovered from the surface only, compared to 14 items where paintwas recovered from the pockets only.
3.3. Size distribution
The longest dimension of each of the 703 recovered paint flakeswas recorded to the nearest 50 μm. The size range of recovered paintflakes was 0.1 mm to 2.9 mm. Eighty percent of the paint flakesrecovered were less than 0.5 mm in length (see Fig. 3).
were classified by type for analysis of the distribution of paint flakes amongst clothing
Total number of paint flakesrecovered
Flakes recovered fromsurfaces
Flakes recovered frompockets
140 68 7255 35 2013 12 150 27 23
192 46 1461 1 03 2 1
45 16 29
68 16 520 0 0
567 223 344
0 10 20 30 40 50 60
CoatCoat
JacketJacketJacket
Waterproof jacketLeather jacketFleece jacketFleece jacket
Hooded jacketHooded jacketHooded jacketHooded jacketHooded jacket
Zip up jacketZip up jacketZip up jacketZip up jacketTracksuit topTracksuit topTracksuit topTracksuit topTracksuit topTracksuit topTracksuit topTracksuit topTracksuit topTracksuit top
CardiganJumperJumperJumper
Zip up topZip up top
Hooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded topHooded top
Hooded Fleece topShirt
T-shirtVest top
Tracksuit trousersTracksuit trousersTracksuit trousers
Jogging bottomsJogging bottoms
Denim JeansDenim JeansDenim JeansDenim JeansDenim Jeans
Gar
ment
type
Number of paint flakes
Number of flakes from surface Number of flakes from pockets
Fig. 2. Comparing the number of paint flakes recovered from the pockets and surfaces of garments. Data from 62 garments with pockets showing the number of paint flakes collectedfrom their surfaces and pockets.
98 R. Moore et al. / Science and Justice 52 (2012) 96–101
Paint flakes recovered from the surfaces of garments were smaller(mean 0.26 mm) compared to flakes recovered from pockets (mean0.47 mm).
3.4. Colour distribution of paint flakes
3.4.1. By topcoat colourThe topcoat colour group of each paint flake recovered was
classified as one of nine colour groups; red, green, blue, grey, orange,white, yellow, brown and black. For other colours, blue/green or
purple for example, the colour description assigned to them using theMethuen Handbook of Colour [5] determined the colour group intowhich they were placed. For example a flake described as greyishgreen would be classed as green.
For themajority of paint flakes examined there were no difficultiesidentifying the topcoat colour. However there were a small number offlakeswhere it was difficult to identifywhichwas the topcoat. In orderto gauge the degree of potential misclassification, the colourdistribution was re-assessed to include just the single layer flakes(see Fig. 4). Comparison of the two data sets showed a small variation
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akes
Fig. 3. Percentage of paint flakes recovered in each size sub-group. All flakes N0.1 mmwere recorded and their longest dimension used to classify them in to size in sub-groups for graphical presentation.
Table 2Number of different top coat colour shades recorded for each of the nine colour groups.The number of identified shades of each colour was limited by the number of colourpanels in each colour group of the Methuen Handbook of Colour. The data presentedtherefore represents a conservative number of colour shades that may be encountered.
Top coat colour Number of paint flakes recovered Number of shades identified
White 185 6Green 99 30Brown 90 12Yellow 87 13Grey 75 5Red 68 16Blue 67 25Black 21 NA⁎
Orange 11 4
⁎ Shades of black not represented in Methuen Handbook of Colour.
71
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3 10
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1 layer 2 layers 3 layers 4+ layers
Nu
mb
er o
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akes
Current study Pearson, May & Dabbs
Fig. 5. Number of paint flakes with one, two, three or four or more paint layers. Layerdata from the current study are compared with the Pearson et al. data.
99R. Moore et al. / Science and Justice 52 (2012) 96–101
of 1–4%. For example, there were 3% fewer single layer blue paintflakes observed compared with the whole data set.
3.4.2. Topcoat colour shadesThe number of colour shades observed within the nine colour
groups are recorded in Table 2.
3.5. Layer sequence analysis
3.5.1. Number of layersThe number of paint layers present within each flake was
recorded. 71% of flakes were single layer, 21% had two layers, 6%exhibited three layers, and the remaining 1% had four or more layers(see Fig. 5). Of the 1% of flakes having four or more layers, 6 flakes had4 layers, 2 flakes had 5 layers, 1 flake had 8 layers and 1 flake had 9layers. It should be noted that the two flakes with eight and ninelayers were both from the same garment and the eight layer sequencewas present in the nine layer flake.
3.5.2. Colours of layersThe combinations of layer sequences encountered from the
recovered paint flakes in this survey are presented in Tables 3–11.
11%
14%
10% 10%
2%
14%
10%
7%
10%
1%
9%
18%
13%
27%
0
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5%
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15%
20%
25%
30%
Grey Green Blue Red Orange
Top c
Per
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akes
rec
ove
red
Top coat of single and multilayer flakes Colo
Fig. 4. Comparing the percentage of recovered paint flakes in each colour group. The distribuflakes only from this study are compared with data from the Pearson et al. study.
All topcoat and under-layer colours are recorded as one of the ninecolour groups described previously.
3.6. Comparison with Pearson, May and Dabbs data
Figs. 5 and 6 illustrate the similarity of the data collected duringthe current study and that of Pearson et al. [1] in respect of the numberof layers and size of recovered paint flakes.
13%
3%
12%
25%
0
14%
2%
14%
28%
0
6%
4% 4%
0
19%
Brown Black Yellow White Cream
oat colour
ur of single layer flakes only Pearson, May & Dabbs
tion of topcoat colour for single andmultilayer paint flakes and the colour of single layer
Table 3Black top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer Number of paint flakes
Black (single layer) – – – 9Black Grey – – 2Black White – – 4Black White Black Grey 1Black Yellow – – 4Black Pink – – 1Total 21
Table 4Brown top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer 5th layer Number of paintflakes
Brown(single layer)
– – – – 70
Brown Black – – – 5Brown White – – – 8Brown Brown Brown – – 1Brown Grey White – – 5Brown Grey Brown Grey White 1Total 90
Table 5Blue top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer Number of paint flakes
Blue (single layer) – – – 38Blue Blue – – 3Blue Blue White 3Blue Brown – – 1Blue White – – 5Blue White Grey 1Blue Yellow – – 3Blue Yellow Grey – 2Blue Grey – – 5Blue Grey Green Grey 1Blue Orange – – 1Blue Black – – 1Blue Red – – 3Total 67
Table 7Grey top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer Number of paint flakes
Grey (single layer) – – – 70Grey White – – 3Grey Blue – – 1Grey Black – – 1Total 75
100 R. Moore et al. / Science and Justice 52 (2012) 96–101
It is difficult to compare the percentage of paint flakes recovered ineach colour group between the two surveys as different groupingmethods have been employed. Fig. 4 illustrates that Pearson et al. [1]
Table 6Green top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer 5th layer
Green (single layer) – – – –
Green Yellow – – –
Green Green – – –
Green Green Yellow – –
Green Green Green – –
Green White – – –
Green White Black – –
Green Black – – –
Green Orange – – –
Green Blue – – –
Green Blue White – –
Green Red – – –
Green Red Black – –
Green Grey – – –
Green Brown Grey Black BrownGreen Green Brown Grey BlackTotal
used a cream category but not white or orange, whereas this surveyrecorded 25% of recovered paint flakes as being white and 2% orange.There were 17% more red flakes recorded in the 1970 surveycompared with the current survey.
The percentage of garments with no paint flakes represents thelargest disparity between the two surveys (28% current survey, 3%Pearson et al. [1]). This may reflect the areas and types of garmentsampled in each study. The current study targeted pockets and surfacesof the ‘every day’wear of individuals suspected of involvement in crime,where as the Pearson et al. [1] survey targeted turn-ups and pockets ofclothes submitted for dry cleaning. Itmaybe that a routinely dry cleanedgarment retains paint flakes in protected areas such as pockets morethan a regularly washed garment. The maximum numbers of flakesobserved on garments between the two studies was similar. However,there is no data on the paint flake exposure of each set of garments. Itmay be that jackets and trousers submitted for dry cleaning are notexposed to the same levels of paint flakes as the ‘every day’ wear ofindividuals suspected of involvement in crime.
4. Application
In the absence of background surveys it is difficult to evaluate thelikelihood of finding a given number of paint flakes of a certain colourand layer sequence, by chance, on the clothingof a person suspected of acrime. Without appropriate data, scientists must rely on their ownexperience and that of their peers and will usually make a conservativeevaluation, which effectively diminishes the evidential value of thefindings in a given case.
Combining discreet elements of the study data, for example thelikelihood of recovering five paint flakes from a garment and for thoseflakes to comprise more than one layer would increase the value ofthe evidential findings of a given case.
However, scientists need to ensure that care is taken when usingthe survey data in support of criminal investigations. The scientistmust be cautious not to double count information. For example whenconsidering the commonness of yellow paints, using the number of
6th layer 7th layer 8th layer 9th layer Number of paint flakes
– – – – 51– – – – 2– – – – 12– – – – 7– – – – 3– – – – 7– – – – 1– – – – 1– – – – 4– – – – 3– – – – 1– – – – 2– – – – 2– – – – 1Black Brown Brown – 1Brown Black Brown Brown 1
99
Table 8Orange top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer Number of paint flakes
Orange (single layer) – – 6Orange White – 3Orange White Grey 1Orange Grey – 1Total 11
Table 9Red top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer Number of paint flakes
Red (single layer) – – – 53Red Black – – 4Red Grey – – 2Red Red – – 3Red White – – 3Red Yellow – – 1Red White Grey 2Total 68
Table 10White top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer 5th layer Number of paintflakes
White(single layer)
– – – – 135
White White – – – 36White White White – – 9White White White White – 3White White Yellow Yellow – 1White Grey – – – 1Total 185
79.8
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m
Flake size (mm)
Per
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akes
re
cove
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Current study Pearson, May & Dabbs
Fig. 6. Comparing the percentage of flake sizes recovered in this study with the Pearsonet al. data. Data from the current study (Fig. 3) were re-classified to match the subgroups in the published data of Pearson et al. to aid comparison.
101R. Moore et al. / Science and Justice 52 (2012) 96–101
yellow shades from the survey data as guidance in addition to anyanalysis data regarding pigmentation could lead to double counting ofinformation, as the pigmentation will be linked to the colour of thepaint that has already been considered.
5. Conclusions
This survey represents avaluableupdateon the1970workperformedbyPearson et al. [1]. The similarities between the twodata sets affirm thatmuch of the 40 year old data remains relevant today.
The distribution study illustrated that empirically, more paint flakeswere recovered from pockets than surfaces. Massonnet and Monnard[6] consider this as an expected outcome and suggest that pockets andcuffs experience a longer retention time in their review of the Pearsonet al. [1] data. For any given garment however, the likelihood of findingpaint flakes on the surface compared with in the pockets was similar.
Table 11Yellow top layer paint flakes recovered and all multi-layer sequences.
1st layer 2nd layer 3rd layer 4th layer 5th layer Number of paintflakes
Yellow(single layer)
– – – – 71
Yellow Orange – – – 5Yellow Orange Grey Brown Brown 1Yellow Green – – – 1Yellow Green Yellow – – 2Yellow Yellow – – – 5Yellow White – – – 2Total 87
Thesizeanalysis results demonstrateda trend for retentionof smallerflakes, with an indication that the relatively protected environment ofpockets contained larger flakes than those retained on the surface of thegarment. Willis et al. [7] have proposed that the persistence of paintparticles resembles that of glass. Glass persistence studies performed byHicks et al. [8] demonstrated a trend for larger fragments to be lost fromclothing more rapidly than smaller ones.
Layer analysis revealed that many-layered flakes are observed lessfrequently compared with single layer flakes. Owing to this relativelyinfrequent observation rate, but mainly to the number and sequenceof layers they possess, a multi-layered paint flake can represent strongevidence of association in a case [9,10]. It is anticipated that the datapresented here will assist and support forensic scientists in evaluatingthe significance of paint evidence recovered from the clothing ofsuspects.
References
[1] E.F. Pearson, R.W. May, M.D.G. Dabbs, Glass and paint fragments found in men'souter clothing — report of a survey, J. of Forensic Sci. 16 (3) (1971) 283–300.
[2] L. Lau, A.D. Beveridge, B.C. Callowhill, N. Conners, K. Foster, R.J. Groves, K.N.Ohashi, A.M. Sumner, H. Wong, The frequency of occurrence of paint and glass onthe clothing of high school students, J. Can. Soc. Forensic Sci. 30 (4) (1997)223–240.
[3] P. Buzzini, G. Massonet, S. Birrer, N. Egli, W. Mazzella, A. Fortini, Survey of crowbarand household paints in burglary cases — populations studies, transfer andinterpretation, Forensic Sci. Int. 152 (2–3) (2005) 221–234.
[4] J.A. Lambert, M.J. Satterthwaite, P.H. Harrison, A survey of glass fragmentsrecovered from clothing of persons suspected of involvement in crime, Sci. Justice35 (4) (1995) 273–281.
[5] A. Kornerup, J.H. Wanscher, Methuen Handbook of Colour, Third ed. Cox andWyman Ltd, Reading, UK, 1978.
[6] G. Massonnet, F. Monnard, Paint: Interpretation, in: A. Jamieson, A. Moenssens(Eds.), Wiley Encyclopedia of Forensic Science, John Wiley & Sons Ltd, WestSussex, 2009, pp. 1943–1954.
[7] S. Willis, J. McCullough, S. McDermott, The interpretation of paint evidence,Forensic Examination of Glass and Paint. Analysis and Interpretation, Taylor andFrancis, New York, 2001, pp. 273–287, 12.
[8] T. Hicks, R. Vanina, P. Margot, Transfer and persistence of glass fragments ongarments, Sci. Justice 36 (1996) 101–107.
[9] R. Saferstein, Criminalistics — An Introduction to Forensic Science, Eighth ed.Prentice Hall, Upper Saddle River, New Jersey, USA, 2004 p222.
[10] H.J. Walls, Forensic Science — An Introduction to Scientific Crime Detection,Second ed., Sweet and Maxwell, London, 1974, pp. 26–40.