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The biter bit: Has DNA fingerprinting made forensic dentistry obsolete? Lauren Aboo Forensic dentistry, or forensic odontology, is the application of dentistry to criminal law, and involves identifying potential criminals or victims from things like their dental records or bite marks; bite mark analysis is one of the most well-known techniques. It includes the comparison of bite marks left on a victim to the potential biters’ dentitions, to determine who the biter was. This can be used to help convict criminals, however ‘bite mark analysis has never passed through the rigorous scientific examination that is common to most normal sciences’ [1], and bite marks are not unique, unlike finger prints [2]. Dental x-rays (radiography records) are used, for example, to compare the teeth of a fire victim to antimortem records of the suspected victim in order to identify the corpse [3]. Alternatively, DNA fingerprinting can identify people not from their teeth but their DNA, which may be left on a victim or at the scene of the crime. DNA from a suspect can be taken from samples such as saliva and can then be compared to the sample from the victim or the scene, to see whether the suspect left the original sample. DNA evidence is widely accepted and is often relied upon over bite mark analysis. For example, the only evidence against American Ray Krone was expert bite mark testimony, and he was sentenced to death for murder in 1992 [2]. However, DNA analysis of blood and saliva left at the scene implicated a convicted rapist; Krone was set free in 2002 [4]. The first, qualitative study concluded that professional odontologists often reach different opinions about the same bite mark, and even disagree upon whether the mark is the result of a bite, and which species the bites came from. The 2015 study concluded that even if individuals’ dentitions are unique, bite marks are not accurate replicas of the biter’s teeth because the skin stretches differently when being bitten and when being measured, distorting the mark so that it is no longer an accurate outline of the biter’s dentition. The third and fourth papers indicate that in the majority of cases, where there is a bite mark there will also be enough DNA to fingerprint, compare to suspects’ DNA, and potentially get a match. Arguably, bite mark analysis used to identify individuals is now obsolete; according to The Intercept, in August 2016, the President’s Council of Advisors on Science and Technology (PCAST) concluded that ‘forensic bite mark evidence is not scientifically valid.’ The PCAST states that bite Introduction Discussion and Conclusions Results SCHOOL OF DENTISTRY Liverpool, L69 3GN, UK. email: [email protected] 1. Modern Scientific Evidence: The Law and Science of Expert Testimony, book by David Laurence Faigman, 2002 – accessed 22nd December 2016 2. Can you catch a killer using only teeth marks? BBC article by Jessica Lussenhop, 15th February 2016, http://www.bbc.co.uk/news/magazine-35564041 - accessed 21st December 2016 3. A note on digital dental radiography in forensic odontology, paper by Sher-Lin Chiam, September to December 2014, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142412/ - accessed 9th January 2017 4. Cases where DNA revealed that bite mark analysis led to wrongful arrests and convictions http://www.innocenceproject.org/cases-where-dna-revealed-that-bite-mark- analysis-led-to-wrongful-arrests-and-convictions/ - accessed 21 st December 2016 5. About bite mark evidence – forensic odontology, The Wrongful Convictions Blog article by Phil Locke, https://globalwrong.files.wordpress.com/2012/09/bundy_bite1.jpg - accessed 16th January 2017 6. Why forensic bite mark analysis lacks teeth, Royal Statistical Society article written by Jim Norton and George Divine, 17th March 2016, https://www.statslife.org.uk/science- technology/2728-why-forensic-bite-mark-analysis-lacks-teeth - accessed 23rd December 2016 7. Expert interpretation of bite mark injuries - a contemporary qualitative study, Journal of Forensic Sciences paper by Mark Page, Jane Taylor, and Matt Blenkin, first published 12 March 2013, http://onlinelibrary.wiley.com/doi/10.1111/1556-4029.12108/full - accessed 22nd December 2016 8. Effects of skin elasticity on bite mark distortion, Forensic Science International paper by Cheri Lewis and Leonor A. Marroquin, 27th July 2015, http://www.fsijournal.org/ article/S0379-0738(15)00326-6/abstract - accessed 22nd December 2016 9. DNA extraction from human saliva deposited on skin and its use in forensic identification procedures, paper by Anzai-Kanto E., Hirata MH, Hirata RD, Nunes FD, Melani RF, and Oliveira RN, September 2005, http://www.scielo.br/scielo.php? script=sci_arttext&pid=S1806-83242005000300011&lng=en&nrm=iso&tlng=en – accessed 16 th January 2017 10. Analysis of salivary DNA evidence from a bite mark on a body submerged in water, Journal of Forensic Science Article by Sweet D and Shutler G.G., September 1999, https://www.ncbi.nlm.nih.gov/pubmed/10486961 - accessed 23rd December 2016 11. White house report concludes that bite mark analysis is junk science, The Intercept article by Jordan Smith, 7th September 2016, https://theintercept.com/2016/09/07/white- house-report-concludes-that-bite-mark-analysis-is-junk-science/ - accessed 23rd December 2016 12. Personal communication from Bryan Kilgallen BDS about how forensic dentistry has changed in the last thirty years, and how it is still relevant to society, 9 th of February 2017 Method A qualitative 2013 study asked 15 odontologists in Australia to comment on whether six potential bite marks came from a human dentition, as well as information such as ‘its quality, orientation, origin, or potential use as an identification tool.’ Opinions varied greatly. About the same photograph, one odontologist commented ‘I know from experience that that’s teeth,’ while another decided that they ‘didn’t think it’s a bite mark… there could be any number of things that could have caused that.’ The researchers concluded that their qualitative data shows professionals have wide ranging opinions on the most fundamental qualities of a bite mark, whether or not it is from a human, because they are using different methods to make their deductions [7]. A 2015 study conceded that while one’s dentition may be unique, bite marks made on the same person when they are in different positions are not. A denture of the anterior maxillary and mandibular teeth was inked and placed on the shoulders of forty subjects aged between 18 and 65. Each person was stamped four times in four different positions, one of which was a control (a total of four stamps each). Individual tooth width varied compared to the control pose depending on the position of the volunteer’s arm by up to 53.8%, and the arch width distortion was as high as 41.9%. Both measurements are used in bite mark analysis, despite this lack of consistency even when the same dentition and victim are used [8]. A Brazilian Oral Research study looked at whether enough DNA could be extracted from a bite mark to identify someone. Samples of saliva from five volunteers were collected, and 250μl of each were rubbed on delimited areas of one researcher's arm, because an estimated 300μl of saliva is deposited when someone is bitten. After ten minutes, dried saliva was taken from the five areas by the double swab technique (wet then dry cotton swabs), then DNA was taken from the swabs. They discovered that ‘recovery of DNA from saliva deposited in the skin was 14 to 10 times lower than DNA quantity from saliva samples (p < 0.05),’ but it was still possible to identify the volunteer that each sample came from by comparing alleles from the same loci [9]. Furthermore, a Journal of Forensic Sciences paper describes a female body retrieved from a river after approximately 5.5 hours submerged under the water. A bite mark was present and saliva from the bite mark was sampled; due to PCR and DNA fingerprinting technology, the perpetrator’s DNA was sequenced and compared to suspects’, contributing to the solution of the case. The authors therefore recommend that bite marks should be swabbed for DNA, ‘even when the amount is thought to be minimal’ [10]. mark analysis relies upon the fact that the human dentition is unique, and that human skin is a reliable substrate to record this individuality, neither of which have been proven [11], unlike DNA fingerprinting, which is widely accepted in the scientific community as reliable and accurate. However, in certain circumstances, bite marks can be accurately used as evidence in courts, for example, in child abuse cases. A forensic odontologist might testify that the child couldn’t have bitten themselves because the bite mark is much too large, helping to prove that the child is being abused. Ultimately, the two sciences are not mutually exclusive; forensic dentists carry out saliva analysis used to fingerprint DNA, and in some situations, comparing antemortem and postmortem dental records is the quickest and most practical solution, for example, identifying fire victims [12]. Thus, I posit that DNA fingerprinting has contributed to the field of dental forensics, not made it obsolete. References Initially, I searched google for ‘DNA fingerprinting’ and ‘forensic dentistry,’ and discovered the most common applications the two had in common were identifying potential criminals, and victims of mass disasters. Because there are so many techniques, I limited my poster to mainly bite mark analysis, with a little about identifying Bite mark from the case of Steven Mark Charney [2]. Bite mark from the case of Ted Bundy [5]. victims of fires using teeth. I couldn't find any relevant research conducted by the University of Liverpool, a lot of statistics weren't specific to what I was researching, and a lot of research was conducted a long time ago (the ‘classic’ study that supports bite marks’ individuality is from 1984 [6]), so it was difficult to find recent papers, but for this I mainly used Google Scholar and PubMed. I also found it difficult to stick to the word count.
Transcript of The biter bit: Has DNA fingerprinting made forensic ...pcpetesmif/posters/Aboo, L.pdf · The biter...
The biter bit: Has DNA fingerprinting made forensic dentistry obsolete? Lauren Aboo
Forensic dentistry, or forensic odontology, is the application of dentistry to criminal law, and involves identifying potential criminals or victims from things like their dental records or bite marks; bite mark analysis is one of the most well-known techniques. It includes the comparison of bite marks left on a victim to the potential biters’ dentitions, to determine who the biter was. This can be used to help convict criminals, however ‘bite mark analysis has never passed through the rigorous scientific examination that is common to most normal sciences’ [1], and bite marks are not unique, unlike finger prints [2]. Dental x-rays (radiography records) are used, for example, to compare the teeth of a fire victim to antimortem records of the suspected victim in order to identify the corpse [3]. Alternatively, DNA fingerprinting can identify people not from their teeth but their DNA, which may be left on a victim or at the scene of the crime. DNA from a suspect can be taken from samples such as saliva and can then be compared to the sample from the victim or the scene, to see whether the suspect left the original sample. DNA evidence is widely accepted and is often relied upon over bite mark analysis. For example, the only evidence against American Ray Krone was expert bite mark testimony, and he was sentenced to death for murder in 1992 [2]. However, DNA analysis of blood and saliva left at the scene implicated a convicted rapist; Krone was set free in 2002 [4].
The first, qualitative study concluded that professional odontologists often reach different opinions about the same bite mark, and even disagree upon whether the mark is the result of a bite, and which species the bites came from. The 2015 study concluded that even if individuals’ dentitions are unique, bite marks are not accurate replicas of the biter’s teeth because the skin stretches differently when being bitten and when being measured, distorting the mark so that it is no longer an accurate outline of the biter’s dentition. The third and fourth papers indicate that in the majority of cases, where there is a bite mark there will also be enough DNA to fingerprint, compare to suspects’ DNA, and potentially get a match. Arguably, bite mark analysis used to identify individuals is now obsolete; according to The Intercept, in August 2016, the President’s Council of Advisors on Science and Technology (PCAST) concluded that ‘forensic bite mark evidence is not scientifically valid.’ The PCAST states that bite
Introduction
Discussion and Conclusions
Results
SCHOOL OF DENTISTRYLiverpool, L69 3GN, UK.
email: [email protected]
1. Modern Scientific Evidence: The Law and Science of Expert Testimony, book by David Laurence Faigman, 2002 – accessed 22nd December 2016 2. Can you catch a killer using only teeth marks? BBC article by Jessica Lussenhop, 15th February 2016, http://www.bbc.co.uk/news/magazine-35564041 - accessed 21st December 2016 3. A note on digital dental radiography in forensic odontology, paper by Sher-Lin Chiam, September to December 2014, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142412/ - accessed 9th January 2017 4. Cases where DNA revealed that bite mark analysis led to wrongful arrests and convictions http://www.innocenceproject.org/cases-where-dna-revealed-that-bite-mark-analysis-led-to-wrongful-arrests-and-convictions/ - accessed 21st December 2016 5. About bite mark evidence – forensic odontology, The Wrongful Convictions Blog article by Phil Locke, https://globalwrong.files.wordpress.com/2012/09/bundy_bite1.jpg - accessed 16th January 2017 6. Why forensic bite mark analysis lacks teeth, Royal Statistical Society article written by Jim Norton and George Divine, 17th March 2016, https://www.statslife.org.uk/science-technology/2728-why-forensic-bite-mark-analysis-lacks-teeth - accessed 23rd December 2016 7. Expert interpretation of bite mark injuries - a contemporary qualitative study, Journal of Forensic Sciences paper by Mark Page, Jane Taylor, and Matt Blenkin, first published 12 March 2013, http://onlinelibrary.wiley.com/doi/10.1111/1556-4029.12108/full - accessed 22nd December 2016 8. Effects of skin elasticity on bite mark distortion, Forensic Science International paper by Cheri Lewis and Leonor A. Marroquin, 27th July 2015, http://www.fsijournal.org/article/S0379-0738(15)00326-6/abstract - accessed 22nd December 2016 9. DNA extraction from human saliva deposited on skin and its use in forensic identification procedures, paper by Anzai-Kanto E., Hirata MH, Hirata RD, Nunes FD, Melani RF, and Oliveira RN, September 2005, http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-83242005000300011&lng=en&nrm=iso&tlng=en – accessed 16th January 2017 10. Analysis of salivary DNA evidence from a bite mark on a body submerged in water, Journal of Forensic Science Article by Sweet D and Shutler G.G., September 1999, https://www.ncbi.nlm.nih.gov/pubmed/10486961 - accessed 23rd December 2016 11. White house report concludes that bite mark analysis is junk science, The Intercept article by Jordan Smith, 7th September 2016, https://theintercept.com/2016/09/07/white-house-report-concludes-that-bite-mark-analysis-is-junk-science/ - accessed 23rd December 2016 12. Personal communication from Bryan Kilgallen BDS about how forensic dentistry has changed in the last thirty years, and how it is still relevant to society, 9th of February 2017
Method
A qualitative 2013 study asked 15 odontologists in Australia to comment on whether six potential bite marks came from a human dentition, as well as information such as ‘its quality, orientation, origin, or potential use as an identification tool.’ Opinions varied greatly. About the same photograph, one odontologist commented ‘I know from experience that that’s teeth,’ while another decided that they ‘didn’t think it’s a bite mark… there could be any number of things that could have caused that.’ The researchers concluded that their qualitative data shows professionals have wide ranging opinions on the most fundamental qualities of a bite mark, whether or not it is from a human, because they are using different methods to make their deductions [7]. !A 2015 study conceded that while one’s dentition may be unique, bite marks made on the same person when they are in different positions are not. A denture of the anterior maxillary and mandibular teeth was inked and placed on the shoulders of forty subjects aged between 18 and 65. Each person was stamped four times in four different positions, one of which was a control (a
total of four stamps each). Individual tooth width varied compared to the control pose depending on the position of the volunteer’s arm by up to 53.8%, and the arch width distortion was as high as 41.9%. Both measurements are used in bite mark analysis, despite this lack of consistency even when the same dentition and victim are used [8]. !A Brazilian Oral Research study looked at whether enough DNA could be extracted from a bite mark to identify someone. Samples of saliva from five volunteers were collected, and 250µl of each were rubbed on delimited areas of
one researcher's arm, because an estimated 300µl of saliva is deposited when someone is bitten. After ten minutes, dried saliva was taken from the five areas by the double swab technique (wet then dry cotton swabs), then DNA was taken from the swabs. They discovered that ‘recovery of DNA from saliva deposited in the skin was 14 to 10 times lower than DNA quantity from saliva samples (p < 0.05),’ but it was still possible to identify the volunteer that each sample came from by comparing alleles from the same loci [9]. !Furthermore, a Journal of Forensic Sciences paper describes a female body retrieved from a river after approximately 5.5 hours submerged under the water. A bite mark was present and saliva from the bite mark was sampled; due to PCR and DNA fingerprinting technology, the perpetrator ’s DNA was sequenced and compared to suspects’, contributing to the solution of the case. The authors therefore recommend that bite marks should be swabbed for DNA, ‘even when the amount is thought to be minimal’ [10].
mark analysis relies upon the fact that the human dentition is unique, and that human skin is a reliable substrate to record this individuality, neither of which have been proven [11], unlike DNA fingerprinting, which is widely accepted in the scientific community as reliable and accurate. However, in certain circumstances, bite marks can be accurately used as evidence in courts, for example, in child abuse cases. A forensic odontologist might testify that the child couldn’t have bitten themselves because the bite mark is much too large, helping to prove that the child is being abused. Ultimately, the two sciences are not mutually exclusive; forensic dentists carry out saliva analysis used to fingerprint DNA, and in some situations, comparing antemortem and postmortem dental records is the quickest and most practical solution, for example, identifying fire victims [12]. Thus, I posit that DNA fingerprinting has contributed to the field of dental forensics, not made it obsolete. !
References
Initially, I searched google for ‘DNA fingerprinting’ and ‘forensic dentistry,’ and discovered the most common applications the two had in common were identifying potential criminals, and victims of mass disasters. Because there are so many techniques, I limited my poster to mainly bite mark analysis, with a little about identifying
Bite mark from the case of Steven Mark Charney [2].
Bite mark from the case of Ted Bundy [5].
victims of fires using teeth. I couldn't find any relevant research conducted by the University of Liverpool, a lot of statistics weren't specific to what I was researching, and a lot of research was conducted a long time ago (the ‘classic’ study that supports bite marks’ individuality is from 1984 [6]), so it was difficult to find recent papers, but for this I mainly used Google Scholar and PubMed. I also found it difficult to stick to the word count.
