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Assessment and prevention of forensic DNA contamination in DNA profiling from latent fingerprint
Forensic Science International: Genetics Supplement Series xxx (xxxx) xxx–xxx
Contents lists available at ScienceDirect
Forensic Science International: Genetics Supplement Series journal homepage: www.elsevier.com/locate/fsigss
Assessment and prevention of forensic DNA contamination in DNA profiling from latent fingerprint Ketsaraporn Nontiapiroma, Wanasphon Bunakkharasawata, Punchapat Sojikulb, ⁎ Nathinee Panvisavasa,c, a
Forensic Science Unit, Faculty of Science, Mahidol University, Thailand Department of Biotechnology, Faculty of Science, Mahidol University, Thailand c Department of Plant Science, Faculty of Science, Mahidol University, Thailand b
A R T I C LE I N FO
A B S T R A C T
Keywords: Fingerprint brush DNA contamination Mixed DNA DNA transfer
In this study, fingerprint brush contamination and a simple brush cleaning procedure was assessed. A total of 10 new camel-hair fingerprint brushes were used for dusting either fresh saliva or saliva stain prior to dusting 4 latent fingerprints deposited on the glass surface. Ten hairs were cut from each fingerprint brush and 4 latent fingerprints were collected by double swab technique for DNA analysis. Consensus DNA profiles were generated from 3 replications of the samples. Result showed that mixed DNA profiles were obtained from the latent fingerprint swabs. More than 2 alleles were observed, and matched alleles from the saliva and fingerprint donors. DNA profiles generated from the brush hairs had no complete loci. The called alleles matched the saliva donor and some were shared alleles of the 2 contributors. Amount of DNA deposited on fresh-saliva contaminated brushes were higher than that those contaminated with saliva stain. Next, fingerprint brushes were cleaned with dish-washing liquid and rinsed with sterile-water. DNA profiling of 5 cleaned-brushes showed that no consensus DNA profile was obtained. Although few alleles were called in each replication of the DNA profile, they were not reproducible. The persistence of biological material on fingerprint brush hairs was demonstrated, thus being a potential source of contamination by indirect material transfer. Cleaning fingerprint brush after direct exposure to biological fluid and stains could help to prevent evidence cross-contamination.
1. Introduction DNA profiling from latent fingerprints is an evidence for linking crime scene to a suspect or a victim. In fact, crime scene examiners repeatedly used fingerprint brushes without cleaning. Therefore, subsequent DNA analysis of powder-dusted latent fingerprints could possibly result in a mixed DNA profile contributed from the primary latent fingerprint itself and/or from various unknown secondary sources. Many factors may affect the transfer of secondary biological materials in the crime scene [1,2]. Fingerprint brush that is used for powderdusting latent fingerprints has showed to be one of the factorthat carried over biological materials. Proff et al. demonstrated that fingerprint brush was one of the factors causing contamination and secondary transfer. Their result indicated that DNA profile could be obtained from routinely-used fingerprint brush [3]. Szkuta et al. established a decontamination process for fingerprint brushes by using 5% Virkon and 1% sodium hypochlorite. They also suggested that DNA
decontamination process in each laboratory should be considered [4]. This study is to assess fingerprint brush contamination process and a simple brush decontamination method. 2. Materials and methods 2.1. Sample preparation and collection New camel fingerprint brushes were used in this study. Background DNA profiles of the 10 new brushes, black powder and sterile glass plates were tested prior use. Fresh saliva and saliva stain were used as the secondary source of transfer in this experiment by spotting 10 μL of fresh saliva on a sterile glass plate. For saliva stain, the 10-μL fresh saliva spot was allowed to completely air-dry before use. Latent fingerprint impressions were generated on clean sterile glass plates. To generate saliva-contaminated black powder-dusted latent
⁎ Corresponding author at: Forensic Science Unit, Faculty of Science, Mahidol University, 272 Rama VI Road, Thung Payathai, Rajathevee, Bangkok, 10400, Thailand. E-mail address: [email protected] (N. Panvisavas).
https://doi.org/10.1016/j.fsigss.2019.10.085 Received 17 September 2019; Accepted 7 October 2019 1875-1768/ © 2019 Elsevier B.V. All rights reserved.
Please cite this article as: Ketsaraporn Nontiapirom, et al., Forensic Science International: Genetics Supplement Series, https://doi.org/10.1016/j.fsigss.2019.10.085
Forensic Science International: Genetics Supplement Series xxx (xxxx) xxx–xxx
K. Nontiapirom, et al.
Fig. 1. Comparisons of (A) number of alleles between saliva donor and fingerprint donor obtained from fingerprint brush hairs and glass surface after brushes were exposed to fresh saliva and saliva stain. (B) number of alleles according to sizes of STR fragments.
fingerprint brushes. These were alleles from D13S317, D19S433, vWA, D18S51, D19S433 and amelogenin. It was noted that these detected alleles from 4 fingerprint brushes were different from saliva donor. Only allele 13.2 matched that of saliva donor at the D19S433 locus. Because the production of fingerprint brushes has no requirement on the control of DNA contamination, the presence of these unknown alleles may be due to previous human contact or contamination. These 10 new brushes were cleaned and confirmed again that no DNA profile was detected from all 10 fingerprint brushes. DNA was recovered and typed from 5 of each fresh and saliva stain contaminated latent fingerprint brush hairs and black powder-dusted latent fingerprint cotton swabs (see Fig. 1A). Analysis of the glass-surface cotton swabs showed that out of a total of 145 alleles in the mixed DNA profile, there were 70 alleles contributed from the fresh saliva donor, 23 alleles contributed from the fingerprint donor and 52 alleles that were shared alleles. On the other hand, a total of 102 alleles were present in the mixed DNA profile, which 23 alleles contributed from saliva stain donor, 45 alleles contributed from the fingerprint donor, and 36 alleles were shared alleles. Results suggested that different level of secondary transfer of the biological material to the surface was due to the different nature of biological material (fresh and biological fluid stain) Exposure of fingerprint brush to fresh saliva resulted in higher level of contamination to the latent fingerprint than stains. Analysis of fingerprint brush hairs showed that out of a total of 75 alleles in the DNA profile, 42 alleles were contributed from the fresh saliva donor and 33 were shared alleles. A very small number of 3 alleles were present in total, in which 1 allele was contributed from the saliva stain contributor and 2 were shared alleles. No alleles from the fingerprint donor was detected on the fingerprint brush hairs. Results suggested that fresh saliva was transferred and persisted on the fingerprint brush hairs at a higher level than saliva stains and no or very low level of biological material from latent fingerprints transfer to the hairs of the fingerprint brush. Considering the sizes of STR alleles (Fig. 1B), results showed that 90–100% of the alleles obtained were smaller than 300 bp,
fingerprints, 5 of each cleaned fingerprint brushes were used to dust over fresh and saliva stains before dusting over 4 latent fingerprints deposited on the glass plates. Dusted latent fingerprints were collected by double swab technique and 10 hairs were randomly clipped from each brush for DNA analysis. 2.2. Brush decontamination All used fingerprint brushes were cleaned by a simple cleaning method. Brushes were rinsed under running tap water in order to remove debris and particulates. Then, they were spun in diluted dishwashing liquid for 15 s and washed under running tap water again before a final rinse by a quick soak in sterile distilled water. Excess water on the cleaned brush was blotted with paper towel and brush was immediately blow-dried using a hair dryer. 2.3. DNA analysis DNA was extracted by Wizard® SV Genomic DNA Purification kit and amount of DNA was estimated by using NanoDrop™ Spectrophotometer. STR was PCR-amplified by using AmpFlSTR Identifiler®PCR Amplification kit with 34 cycles and analyzed by ABI Prism® 310 Genetic Analyzer. Consensus DNA profile was generated from 3 replications of DNA profiling. Number of loci, no. of alleles, and size of recovered alleles from fingerprint donor, saliva donor and shared alleles were observed. 3. Results and discussion Background DNA on sterile glass plate, 10 new fingerprint brushes and 0.003 g of new black powder were tested before starting the experiment. The result showed that no STR alleles was found from sterile glass plate and new black powder. However, analysis of 10 new fingerprint brushes showed that 1–2 alleles were detected from 5 new 2
Forensic Science International: Genetics Supplement Series xxx (xxxx) xxx–xxx
K. Nontiapirom, et al.
whereas 0–10% were larger than 300 bp. Experimental results provided support that the transfer of biological material from a secondary source (saliva) occurred via fingerprint brush. The nature of biological material resulted in different level of persistence on the brush hair and transfer to a new area. Ten used fingerprint brushes were decontaminated by using a simple decontamination method according to 2.2. The result showed that no consensus DNA profile was obtained from 5 cleaned-brushes. (Data not shown).
method proposed in this study could help reduce contamination from the brush. This would be promising to apply in practice and would benefit the crime scene investigation.
4. Conclusion
Poster presentation at ISFG 2019 was partially supported by Faculty of Science, and Faculty of Graduate Studies, Mahidol University.
Declaration of Competing Interest None. Acknowledgements
This study demonstrated that fingerprint brush could be a critical carrier that caused secondary transfer of biological materials to fingerprint evidence. Analysis of fingerprint brush hairs showed persistence of biological materials that exposed to the fingerprint brush after dusting if the biological materials was fresh/wet. More DNA could accumulate and persist on the fingerprint brush when exposing to fresh/ wet biological specimens than completely dried stains. Quality and quantity of allele on DNA profile depend on nature of the stain. Awareness must be taken if the fingerprint brush exposed to biological materials, especially fresh biological fluids, and continuously used in crime scene investigation. A simple and time-saving decontamination
References [1] M. Goray, E. Eken, R.J. Mitchell, et al., Secondary DNA transfer of biological substances under varying test conditions, Forensic Sci. Int. Genet. 4 (2) (2010) 62–67. [2] R.A.H. van Oorschot, B. Szkuta, G.E. Meakin, et al., DNA transfer in forensic science: a review, Forensic Sci. Int. Genet. 38 (2019) 140–166. [3] C. Proff, C. Schmitt, P.M. Schneider, et al., Experiments on the DNA contamination risk via latent fingerprint brushes, Int. Congr. Ser. 1288 (2006) 601–603. [4] B. Szkuta, O. RAHv, K.N. Ballantyne, DNA decontamination of fingerprint brushes, Forensic Sci. Int. 277 (2017) 41–50.
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Contents lists available at ScienceDirect
Forensic Science International: Genetics Supplement Series journal homepage: www.elsevier.com/locate/fsigss
Assessment and prevention of forensic DNA contamination in DNA profiling from latent fingerprint Ketsaraporn Nontiapiroma, Wanasphon Bunakkharasawata, Punchapat Sojikulb, ⁎ Nathinee Panvisavasa,c, a
Forensic Science Unit, Faculty of Science, Mahidol University, Thailand Department of Biotechnology, Faculty of Science, Mahidol University, Thailand c Department of Plant Science, Faculty of Science, Mahidol University, Thailand b
A R T I C LE I N FO
A B S T R A C T
Keywords: Fingerprint brush DNA contamination Mixed DNA DNA transfer
In this study, fingerprint brush contamination and a simple brush cleaning procedure was assessed. A total of 10 new camel-hair fingerprint brushes were used for dusting either fresh saliva or saliva stain prior to dusting 4 latent fingerprints deposited on the glass surface. Ten hairs were cut from each fingerprint brush and 4 latent fingerprints were collected by double swab technique for DNA analysis. Consensus DNA profiles were generated from 3 replications of the samples. Result showed that mixed DNA profiles were obtained from the latent fingerprint swabs. More than 2 alleles were observed, and matched alleles from the saliva and fingerprint donors. DNA profiles generated from the brush hairs had no complete loci. The called alleles matched the saliva donor and some were shared alleles of the 2 contributors. Amount of DNA deposited on fresh-saliva contaminated brushes were higher than that those contaminated with saliva stain. Next, fingerprint brushes were cleaned with dish-washing liquid and rinsed with sterile-water. DNA profiling of 5 cleaned-brushes showed that no consensus DNA profile was obtained. Although few alleles were called in each replication of the DNA profile, they were not reproducible. The persistence of biological material on fingerprint brush hairs was demonstrated, thus being a potential source of contamination by indirect material transfer. Cleaning fingerprint brush after direct exposure to biological fluid and stains could help to prevent evidence cross-contamination.
1. Introduction DNA profiling from latent fingerprints is an evidence for linking crime scene to a suspect or a victim. In fact, crime scene examiners repeatedly used fingerprint brushes without cleaning. Therefore, subsequent DNA analysis of powder-dusted latent fingerprints could possibly result in a mixed DNA profile contributed from the primary latent fingerprint itself and/or from various unknown secondary sources. Many factors may affect the transfer of secondary biological materials in the crime scene [1,2]. Fingerprint brush that is used for powderdusting latent fingerprints has showed to be one of the factorthat carried over biological materials. Proff et al. demonstrated that fingerprint brush was one of the factors causing contamination and secondary transfer. Their result indicated that DNA profile could be obtained from routinely-used fingerprint brush [3]. Szkuta et al. established a decontamination process for fingerprint brushes by using 5% Virkon and 1% sodium hypochlorite. They also suggested that DNA
decontamination process in each laboratory should be considered [4]. This study is to assess fingerprint brush contamination process and a simple brush decontamination method. 2. Materials and methods 2.1. Sample preparation and collection New camel fingerprint brushes were used in this study. Background DNA profiles of the 10 new brushes, black powder and sterile glass plates were tested prior use. Fresh saliva and saliva stain were used as the secondary source of transfer in this experiment by spotting 10 μL of fresh saliva on a sterile glass plate. For saliva stain, the 10-μL fresh saliva spot was allowed to completely air-dry before use. Latent fingerprint impressions were generated on clean sterile glass plates. To generate saliva-contaminated black powder-dusted latent
⁎ Corresponding author at: Forensic Science Unit, Faculty of Science, Mahidol University, 272 Rama VI Road, Thung Payathai, Rajathevee, Bangkok, 10400, Thailand. E-mail address: [email protected] (N. Panvisavas).
https://doi.org/10.1016/j.fsigss.2019.10.085 Received 17 September 2019; Accepted 7 October 2019 1875-1768/ © 2019 Elsevier B.V. All rights reserved.
Please cite this article as: Ketsaraporn Nontiapirom, et al., Forensic Science International: Genetics Supplement Series, https://doi.org/10.1016/j.fsigss.2019.10.085
Forensic Science International: Genetics Supplement Series xxx (xxxx) xxx–xxx
K. Nontiapirom, et al.
Fig. 1. Comparisons of (A) number of alleles between saliva donor and fingerprint donor obtained from fingerprint brush hairs and glass surface after brushes were exposed to fresh saliva and saliva stain. (B) number of alleles according to sizes of STR fragments.
fingerprint brushes. These were alleles from D13S317, D19S433, vWA, D18S51, D19S433 and amelogenin. It was noted that these detected alleles from 4 fingerprint brushes were different from saliva donor. Only allele 13.2 matched that of saliva donor at the D19S433 locus. Because the production of fingerprint brushes has no requirement on the control of DNA contamination, the presence of these unknown alleles may be due to previous human contact or contamination. These 10 new brushes were cleaned and confirmed again that no DNA profile was detected from all 10 fingerprint brushes. DNA was recovered and typed from 5 of each fresh and saliva stain contaminated latent fingerprint brush hairs and black powder-dusted latent fingerprint cotton swabs (see Fig. 1A). Analysis of the glass-surface cotton swabs showed that out of a total of 145 alleles in the mixed DNA profile, there were 70 alleles contributed from the fresh saliva donor, 23 alleles contributed from the fingerprint donor and 52 alleles that were shared alleles. On the other hand, a total of 102 alleles were present in the mixed DNA profile, which 23 alleles contributed from saliva stain donor, 45 alleles contributed from the fingerprint donor, and 36 alleles were shared alleles. Results suggested that different level of secondary transfer of the biological material to the surface was due to the different nature of biological material (fresh and biological fluid stain) Exposure of fingerprint brush to fresh saliva resulted in higher level of contamination to the latent fingerprint than stains. Analysis of fingerprint brush hairs showed that out of a total of 75 alleles in the DNA profile, 42 alleles were contributed from the fresh saliva donor and 33 were shared alleles. A very small number of 3 alleles were present in total, in which 1 allele was contributed from the saliva stain contributor and 2 were shared alleles. No alleles from the fingerprint donor was detected on the fingerprint brush hairs. Results suggested that fresh saliva was transferred and persisted on the fingerprint brush hairs at a higher level than saliva stains and no or very low level of biological material from latent fingerprints transfer to the hairs of the fingerprint brush. Considering the sizes of STR alleles (Fig. 1B), results showed that 90–100% of the alleles obtained were smaller than 300 bp,
fingerprints, 5 of each cleaned fingerprint brushes were used to dust over fresh and saliva stains before dusting over 4 latent fingerprints deposited on the glass plates. Dusted latent fingerprints were collected by double swab technique and 10 hairs were randomly clipped from each brush for DNA analysis. 2.2. Brush decontamination All used fingerprint brushes were cleaned by a simple cleaning method. Brushes were rinsed under running tap water in order to remove debris and particulates. Then, they were spun in diluted dishwashing liquid for 15 s and washed under running tap water again before a final rinse by a quick soak in sterile distilled water. Excess water on the cleaned brush was blotted with paper towel and brush was immediately blow-dried using a hair dryer. 2.3. DNA analysis DNA was extracted by Wizard® SV Genomic DNA Purification kit and amount of DNA was estimated by using NanoDrop™ Spectrophotometer. STR was PCR-amplified by using AmpFlSTR Identifiler®PCR Amplification kit with 34 cycles and analyzed by ABI Prism® 310 Genetic Analyzer. Consensus DNA profile was generated from 3 replications of DNA profiling. Number of loci, no. of alleles, and size of recovered alleles from fingerprint donor, saliva donor and shared alleles were observed. 3. Results and discussion Background DNA on sterile glass plate, 10 new fingerprint brushes and 0.003 g of new black powder were tested before starting the experiment. The result showed that no STR alleles was found from sterile glass plate and new black powder. However, analysis of 10 new fingerprint brushes showed that 1–2 alleles were detected from 5 new 2
Forensic Science International: Genetics Supplement Series xxx (xxxx) xxx–xxx
K. Nontiapirom, et al.
whereas 0–10% were larger than 300 bp. Experimental results provided support that the transfer of biological material from a secondary source (saliva) occurred via fingerprint brush. The nature of biological material resulted in different level of persistence on the brush hair and transfer to a new area. Ten used fingerprint brushes were decontaminated by using a simple decontamination method according to 2.2. The result showed that no consensus DNA profile was obtained from 5 cleaned-brushes. (Data not shown).
method proposed in this study could help reduce contamination from the brush. This would be promising to apply in practice and would benefit the crime scene investigation.
4. Conclusion
Poster presentation at ISFG 2019 was partially supported by Faculty of Science, and Faculty of Graduate Studies, Mahidol University.
Declaration of Competing Interest None. Acknowledgements
This study demonstrated that fingerprint brush could be a critical carrier that caused secondary transfer of biological materials to fingerprint evidence. Analysis of fingerprint brush hairs showed persistence of biological materials that exposed to the fingerprint brush after dusting if the biological materials was fresh/wet. More DNA could accumulate and persist on the fingerprint brush when exposing to fresh/ wet biological specimens than completely dried stains. Quality and quantity of allele on DNA profile depend on nature of the stain. Awareness must be taken if the fingerprint brush exposed to biological materials, especially fresh biological fluids, and continuously used in crime scene investigation. A simple and time-saving decontamination
References [1] M. Goray, E. Eken, R.J. Mitchell, et al., Secondary DNA transfer of biological substances under varying test conditions, Forensic Sci. Int. Genet. 4 (2) (2010) 62–67. [2] R.A.H. van Oorschot, B. Szkuta, G.E. Meakin, et al., DNA transfer in forensic science: a review, Forensic Sci. Int. Genet. 38 (2019) 140–166. [3] C. Proff, C. Schmitt, P.M. Schneider, et al., Experiments on the DNA contamination risk via latent fingerprint brushes, Int. Congr. Ser. 1288 (2006) 601–603. [4] B. Szkuta, O. RAHv, K.N. Ballantyne, DNA decontamination of fingerprint brushes, Forensic Sci. Int. 277 (2017) 41–50.
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