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The transfer of glass—part 4
Forensic Science International 93 (1998) 201–208
The transfer of glass—part 4 The transfer of glass fragments from the surface of an item to the person carrying it a, a b b a T.J. Allen *, A.R. Cox , S. Barton , P. Messam , J.A. Lambert a
Service Development, Priory House, Gooch Street North, Birmingham B5 6 QQ , UK b Kings College, The Strand, London, UK
Received 2 May 1997; received in revised form 18 December 1997; accepted 22 February 1998
Abstract The transfer of glass from the outer surface of a cardboard box to the clothing of a person carrying the box was investigated. In these experiments the box was placed 1 m behind a window which was subsequently broken. Glass was found on the box after all breakings, with more than 200 fragments on the surface in 7 out of 12 experiments. Between 1 and 22 fragments were recovered from the clothing (upper bodywear and legwear) of the person carrying the box. The distribution of fragment size and shape was similar to those described in previous studies. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Criminalistics; Glass; Transfer
1. Introduction A number of studies have investigated the fragment size distribution and the extent to which glass is transferred to the clothing of a suspect when breaking a window [1–7]. This process has been referred to as primary transfer, via backward fragmentation. One study looked at the distribution of fragment size and shape when breaking a window or brushing up the broken glass [8]. There is also a possibility of the transfer of glass from one person or object to another person; this process is called secondary transfer. There have been several studies in this *Corresponding author. 0379-0738 / 98 / $19.00 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0379-0738( 98 )00044-9
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area. Holcroft and Shearer [9] showed that about 10% of glass fragments on the clothing of a person who broke a window could be transferred to a second person by firm physical contact. Similar results were obtained by Bone [10] in which a large number of glass fragments were placed on a donor garment. Allen et al. [11] investigated the transfer of glass between two people in a car and found that only one fragment was transferred in 15 experiments. Fragments from a breaking window may fall on to items nearby. In this work, glass has been found on the floor up to 4.0 m behind a broken window, by forward fragmentation. If a person handles items contaminated with glass from this forward fragmentation, it is possible that fragments could be transferred to their clothing. This work investigates the transfer of glass to a person carrying a cardboard box contaminated with glass. The experiments were repeated for 3 clothing types. Some information was also obtained on the quantity of glass found on an object removed from behind a broken window.
2. Experimental
2.1. Breaking rig A breaking rig was designed which allowed window panes to be clamped such that the bottom of the window was 0.9 m from the floor. The pane of glass (0.4830.59 m34 mm) was clamped in the frame with wooden strips against rubber foam. A sealed cardboard box (approximately 30330330 cm) was placed on the floor, 0.5 m behind the window. This mimicked items in a room gaining glass on their surfaces when the window was broken. The window was broken slightly above centre with a single blow from a crowbar by a person standing slightly to the right, 0.5 m from the window.
2.2. Clothing Three garment types were worn by the person carrying the box: shellsuits (100% nylon)—low retention; tracksuits (cotton / acrylic / polyester blend 45 / 40 / 15)—medium retention; jumper (100% acrylic) with denim jeans—both medium retention. The clothes were those used in previous transfer experiments [5] except for the jeans which were purchased from a local shop. The clothes were worn over a scene suit.
2.3. Experimental procedure The window was broken and the person moved away. A different individual, wearing one of the three clothing types, walked over the broken glass on the floor to the breaking rig. The individual tipped the box in a direction away from themselves, to remove any large loose fragments, and then picked the box up. The individual walked a distance of approximately 10 m holding the box against their chest and placed it on a debris sheet on the floor. The debris sheet consisted of two sheets of paper (131 m) placed on top of each other. The individual then removed their footwear and undressed on a separate
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debris sheet. The upper bodywear and legwear were placed into separate paper bags and sealed. The experiment was repeated four times for each clothing type.
2.4. Searching The clothing was searched by holding the garments upright as they would be worn, over two large sheets of brown paper, shaking, then vigorously brushing with a flat hand. The experimental design was such that it was unlikely for glass to transfer to the pockets, hence the pockets were not searched. The debris was collected in plastic petri dishes. Debris from the surface of the box was collected by tipping and banging the sides of the box over the sheet onto which it had been placed. The debris was then transferred to a plastic petri dish. The contents of each petri dish were examined under a Nikon stereomicroscope (340) and the number of fragments was recorded, or estimated if more than 200 fragments were present. The authors realise that this magnification is greater than normally used in case work, however, it allowed the smaller sized fragments to be examined for this work. For the clothing debris, the size and shape of the glass fragments were also recorded. Size was recorded as 0.1–0.25, 0.25–0.5, 0.5–1.0 mm or greater than 1 mm, according to the largest dimension. The shape was classed as flake, chunk or needle [8]. A fragment with one long dimension and two short dimensions in a ratio 10:1 or greater was a needle. If there were two long dimensions to one short dimension with an aspect ratio of 10:1 or greater then the fragment was a flake. Any fragment that did not fit in these categories was a chunk.
Fig. 1. The distribution of the number of fragments on a cardboard box after it has been picked up, carried 10 m and placed on a debris sheet.
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Fig. 2. The number of fragments transferred to a person carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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Fig. 3. The distribution of fragments by size transferred to a person (including debris sheets) carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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Fig. 4. The distribution of glass fragments by shape when transferred to a person (including debris sheets) carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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3. Results and discussion The distribution of the number of fragments remaining on the box is shown in Fig. 1. The fragments ranged from 0.1–4 mm in size. On 7 out of 12 occasions, more than 200 fragments where found on the box. There were, therefore, a large number of fragments which could have been transferred to the person carrying the box. Fig. 2 shows the number of fragments found on the clothing of a person carrying a box contaminated with glass fragments. Between 1 and 22 glass fragments were recovered from each set of clothing (upper bodywear and legwear). In general tracksuits appear to have fewer fragments on them compared to the shellsuits or jeans with jumpers. These results are at the low end of the range of fragments recovered from clothes when breaking a window [5]. The debris sheet on which the person undressed contained 0 to 43 fragments which represents 0–77% of fragments transferred from the box to the clothes. This was calculated by dividing the number of fragments on the debris sheet by the total fragments recovered from the clothing and debris sheet, for each experiment. The authors have no explanation for the wide range found on the debris sheet. It is probable that the glass transferred from the box will be lightly attached to the surface of the clothing, and hence readily lost when the clothing is removed. Fig. 3 shows the distribution of fragments by size on each of the 3 clothing types including debris sheets. The distribution for tracksuits is similar to that found by primary transfer during persistence experiments using the same clothes [12], while the distributions for shellsuits and jeans with jumper show less fragments above 0.5 mm. Fig. 4 shows the distribution of fragment shape on the 3 types of clothes including debris sheets. The distribution for tracksuits and jeans with jumpers shows some agreement with previous work using the same clothing [12] and also with the work by Underhill [8]. Shellsuits have a greater proportion of flake shaped fragments; in one experiment 20 out of 21 fragments recovered from the clothing were classified as flakes. When compared to previous work [12] the proportion of flakes found on shellsuits was high.
4. Conclusions
1. In 7 out of 12 of the experiments more than 200 glass fragments were recovered from the surface of a box, after it had been carried a distance of 10 metres. 2. In every experiment, glass was transferred to the clothing of the person who carried the box. 3. The distribution of fragments by size and shape is not sufficiently characteristic to distinguish it from that expected as a result of primary transfer.
References [1] J. Locke, J.A. Unikowski, Breaking of flat glass—part 1: Size and distribution of particles from plain glass windows, Forensic Sci. Int. 51 (1991) 251–262.
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[2] J. Locke, J.A. Unikowski, Breaking of flat glass—part 2: Effect of pane parameters on particle distribution, Forensic Sci. Int. 56 (1992) 95–106. [3] J. Locke, J.K. Scranage, Breaking of flat glass—part 3: Surface particles from windows, Forensic Sci. Int. 57 (1992) 73–80. [4] T.J. Allen, K. J, Scranage, The transfer of glass—part 1: Transfer of glass to individuals at different distances, Forensic Sci. Int. 93 (1998) 167–174. [5] T.J. Allen, K. Hoefler, S.J. Rose, The transfer of glass—part 2: A study of the transfer of glass to a person during various activities, Forensic Sci. Int. 93 (1998) 175–193. [6] R.J.W. Luce, J.L. Buckle, I. Mcinnis, A study on the backward fragmentation of window glass and the transfer of glass fragments to individual’s clothing, J. Canadian Soc. Forensic Sci. 24(2) (1991) 79–89. [7] T. Hicks, R. Vanina, P. Margot, Transfer persistence of glass fragments on garments, Sci. Justice 36(2) (1996) 101–107. [8] M. Underhill, The acquisition of breaking and broken glass, Sci. Justice 37(2) (1997) 121–127. [9] G.A. Holcroft, B. Shearer, Personnel communication. [10] R.G. Bone, Personnel communication. [11] T.J. Allen, K. Hoefler, S.J. Rose, The transfer of glass—part 3: The transfer of glass from a contaminated person to another uncontaminated person during a ride in a car, Forensic Sci. Int. 93 (1998) 195–200. [12] T.J. Allen, A.R. Cox, S. Barton, P. Messam, J.A. Lambert, The persistence of glass. Part 2: The effects of fragment size and shape, Forensic Sci. Int. (1998) in press.
The transfer of glass—part 4 The transfer of glass fragments from the surface of an item to the person carrying it a, a b b a T.J. Allen *, A.R. Cox , S. Barton , P. Messam , J.A. Lambert a
Service Development, Priory House, Gooch Street North, Birmingham B5 6 QQ , UK b Kings College, The Strand, London, UK
Received 2 May 1997; received in revised form 18 December 1997; accepted 22 February 1998
Abstract The transfer of glass from the outer surface of a cardboard box to the clothing of a person carrying the box was investigated. In these experiments the box was placed 1 m behind a window which was subsequently broken. Glass was found on the box after all breakings, with more than 200 fragments on the surface in 7 out of 12 experiments. Between 1 and 22 fragments were recovered from the clothing (upper bodywear and legwear) of the person carrying the box. The distribution of fragment size and shape was similar to those described in previous studies. 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Criminalistics; Glass; Transfer
1. Introduction A number of studies have investigated the fragment size distribution and the extent to which glass is transferred to the clothing of a suspect when breaking a window [1–7]. This process has been referred to as primary transfer, via backward fragmentation. One study looked at the distribution of fragment size and shape when breaking a window or brushing up the broken glass [8]. There is also a possibility of the transfer of glass from one person or object to another person; this process is called secondary transfer. There have been several studies in this *Corresponding author. 0379-0738 / 98 / $19.00 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0379-0738( 98 )00044-9
202
T. J. Allen et al. / Forensic Science International 93 (1998) 201 – 208
area. Holcroft and Shearer [9] showed that about 10% of glass fragments on the clothing of a person who broke a window could be transferred to a second person by firm physical contact. Similar results were obtained by Bone [10] in which a large number of glass fragments were placed on a donor garment. Allen et al. [11] investigated the transfer of glass between two people in a car and found that only one fragment was transferred in 15 experiments. Fragments from a breaking window may fall on to items nearby. In this work, glass has been found on the floor up to 4.0 m behind a broken window, by forward fragmentation. If a person handles items contaminated with glass from this forward fragmentation, it is possible that fragments could be transferred to their clothing. This work investigates the transfer of glass to a person carrying a cardboard box contaminated with glass. The experiments were repeated for 3 clothing types. Some information was also obtained on the quantity of glass found on an object removed from behind a broken window.
2. Experimental
2.1. Breaking rig A breaking rig was designed which allowed window panes to be clamped such that the bottom of the window was 0.9 m from the floor. The pane of glass (0.4830.59 m34 mm) was clamped in the frame with wooden strips against rubber foam. A sealed cardboard box (approximately 30330330 cm) was placed on the floor, 0.5 m behind the window. This mimicked items in a room gaining glass on their surfaces when the window was broken. The window was broken slightly above centre with a single blow from a crowbar by a person standing slightly to the right, 0.5 m from the window.
2.2. Clothing Three garment types were worn by the person carrying the box: shellsuits (100% nylon)—low retention; tracksuits (cotton / acrylic / polyester blend 45 / 40 / 15)—medium retention; jumper (100% acrylic) with denim jeans—both medium retention. The clothes were those used in previous transfer experiments [5] except for the jeans which were purchased from a local shop. The clothes were worn over a scene suit.
2.3. Experimental procedure The window was broken and the person moved away. A different individual, wearing one of the three clothing types, walked over the broken glass on the floor to the breaking rig. The individual tipped the box in a direction away from themselves, to remove any large loose fragments, and then picked the box up. The individual walked a distance of approximately 10 m holding the box against their chest and placed it on a debris sheet on the floor. The debris sheet consisted of two sheets of paper (131 m) placed on top of each other. The individual then removed their footwear and undressed on a separate
T. J. Allen et al. / Forensic Science International 93 (1998) 201 – 208
203
debris sheet. The upper bodywear and legwear were placed into separate paper bags and sealed. The experiment was repeated four times for each clothing type.
2.4. Searching The clothing was searched by holding the garments upright as they would be worn, over two large sheets of brown paper, shaking, then vigorously brushing with a flat hand. The experimental design was such that it was unlikely for glass to transfer to the pockets, hence the pockets were not searched. The debris was collected in plastic petri dishes. Debris from the surface of the box was collected by tipping and banging the sides of the box over the sheet onto which it had been placed. The debris was then transferred to a plastic petri dish. The contents of each petri dish were examined under a Nikon stereomicroscope (340) and the number of fragments was recorded, or estimated if more than 200 fragments were present. The authors realise that this magnification is greater than normally used in case work, however, it allowed the smaller sized fragments to be examined for this work. For the clothing debris, the size and shape of the glass fragments were also recorded. Size was recorded as 0.1–0.25, 0.25–0.5, 0.5–1.0 mm or greater than 1 mm, according to the largest dimension. The shape was classed as flake, chunk or needle [8]. A fragment with one long dimension and two short dimensions in a ratio 10:1 or greater was a needle. If there were two long dimensions to one short dimension with an aspect ratio of 10:1 or greater then the fragment was a flake. Any fragment that did not fit in these categories was a chunk.
Fig. 1. The distribution of the number of fragments on a cardboard box after it has been picked up, carried 10 m and placed on a debris sheet.
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Fig. 2. The number of fragments transferred to a person carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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Fig. 3. The distribution of fragments by size transferred to a person (including debris sheets) carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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Fig. 4. The distribution of glass fragments by shape when transferred to a person (including debris sheets) carrying a contaminated box while wearing: (a) tracksuits; (b) shellsuits; (c) jeans with jumpers.
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3. Results and discussion The distribution of the number of fragments remaining on the box is shown in Fig. 1. The fragments ranged from 0.1–4 mm in size. On 7 out of 12 occasions, more than 200 fragments where found on the box. There were, therefore, a large number of fragments which could have been transferred to the person carrying the box. Fig. 2 shows the number of fragments found on the clothing of a person carrying a box contaminated with glass fragments. Between 1 and 22 glass fragments were recovered from each set of clothing (upper bodywear and legwear). In general tracksuits appear to have fewer fragments on them compared to the shellsuits or jeans with jumpers. These results are at the low end of the range of fragments recovered from clothes when breaking a window [5]. The debris sheet on which the person undressed contained 0 to 43 fragments which represents 0–77% of fragments transferred from the box to the clothes. This was calculated by dividing the number of fragments on the debris sheet by the total fragments recovered from the clothing and debris sheet, for each experiment. The authors have no explanation for the wide range found on the debris sheet. It is probable that the glass transferred from the box will be lightly attached to the surface of the clothing, and hence readily lost when the clothing is removed. Fig. 3 shows the distribution of fragments by size on each of the 3 clothing types including debris sheets. The distribution for tracksuits is similar to that found by primary transfer during persistence experiments using the same clothes [12], while the distributions for shellsuits and jeans with jumper show less fragments above 0.5 mm. Fig. 4 shows the distribution of fragment shape on the 3 types of clothes including debris sheets. The distribution for tracksuits and jeans with jumpers shows some agreement with previous work using the same clothing [12] and also with the work by Underhill [8]. Shellsuits have a greater proportion of flake shaped fragments; in one experiment 20 out of 21 fragments recovered from the clothing were classified as flakes. When compared to previous work [12] the proportion of flakes found on shellsuits was high.
4. Conclusions
1. In 7 out of 12 of the experiments more than 200 glass fragments were recovered from the surface of a box, after it had been carried a distance of 10 metres. 2. In every experiment, glass was transferred to the clothing of the person who carried the box. 3. The distribution of fragments by size and shape is not sufficiently characteristic to distinguish it from that expected as a result of primary transfer.
References [1] J. Locke, J.A. Unikowski, Breaking of flat glass—part 1: Size and distribution of particles from plain glass windows, Forensic Sci. Int. 51 (1991) 251–262.
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T. J. Allen et al. / Forensic Science International 93 (1998) 201 – 208
[2] J. Locke, J.A. Unikowski, Breaking of flat glass—part 2: Effect of pane parameters on particle distribution, Forensic Sci. Int. 56 (1992) 95–106. [3] J. Locke, J.K. Scranage, Breaking of flat glass—part 3: Surface particles from windows, Forensic Sci. Int. 57 (1992) 73–80. [4] T.J. Allen, K. J, Scranage, The transfer of glass—part 1: Transfer of glass to individuals at different distances, Forensic Sci. Int. 93 (1998) 167–174. [5] T.J. Allen, K. Hoefler, S.J. Rose, The transfer of glass—part 2: A study of the transfer of glass to a person during various activities, Forensic Sci. Int. 93 (1998) 175–193. [6] R.J.W. Luce, J.L. Buckle, I. Mcinnis, A study on the backward fragmentation of window glass and the transfer of glass fragments to individual’s clothing, J. Canadian Soc. Forensic Sci. 24(2) (1991) 79–89. [7] T. Hicks, R. Vanina, P. Margot, Transfer persistence of glass fragments on garments, Sci. Justice 36(2) (1996) 101–107. [8] M. Underhill, The acquisition of breaking and broken glass, Sci. Justice 37(2) (1997) 121–127. [9] G.A. Holcroft, B. Shearer, Personnel communication. [10] R.G. Bone, Personnel communication. [11] T.J. Allen, K. Hoefler, S.J. Rose, The transfer of glass—part 3: The transfer of glass from a contaminated person to another uncontaminated person during a ride in a car, Forensic Sci. Int. 93 (1998) 195–200. [12] T.J. Allen, A.R. Cox, S. Barton, P. Messam, J.A. Lambert, The persistence of glass. Part 2: The effects of fragment size and shape, Forensic Sci. Int. (1998) in press.