Forensic Analysis: Weighing Bullet Lead Evidence

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Evidence 4. Discovery 3. Procedural Rights 3. Advocacy 2. Death Penalty 2. News Release Document 5. Content Page 2. We're sorry, something went wrong. Please try again. About this product. Stock photo. Pre-owned: lowest price The lowest-priced item that has been used or worn previously. Paperback in Good condition They are not actual photos of the physical item for sale and should not be relied upon as a basis for edition or condition.

See details. See all 2 pre-owned listings. Buy It Now. Add to cart. Assume, however, an optimal case: sufficient information from source dentition exists and has been impressed upon a stable substrate on a victim's body; that sound methods have been employed to visualize and compare the bite mark on the victim and a suspect's dentition; that valid criteria have been developed for deciding when to include and when to exclude dentition as a possible source; and that a forensic dentist has reached a justifiable conclusion that the images were sufficiently similar to include.

The next step would be to assess what that decision can tell a factfinder about the likelihood that the suspected person's dentition did in fact produce the bite mark. As discussed earlier, such an evaluation depends upon estimating the frequency of similar patterns in the relevant population.

Unfortunately, forensic dentists have very little information of the kind needed to make an informed assessment.

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This was especially true in analysis of orthodontically treated dentitions, in which dental arrangements are purposely made homologous. In the absence of data concerning population frequencies of dental characteristics, how have forensic dentists assessed the value of an inclusion? One way has been to speculate or guesstimate about the population frequencies of the characteristics of biting teeth. A forensic dentist might judge a bite mark to have been made by a pattern of teeth that seems unusual in his or her experience. On occasion, a source's teeth are so unusual that they are obvious outliers; then, when a suspect's teeth are deemed closely similar a well-defined bite mark, impressed into a stable substrate , the probability is smaller that a different person will have produced the bite mark.

There is no escaping the fact that forensic identification is an essentially probabilistic endeavor. For the great majority of bite marks, however, population frequencies will necessarily be higher than in the very unusual cases, and the risk of erroneous identification greater. An even stronger claim is being made by forensic dentistry: not only that all dentitions are unique, but also that every bite mark produced by those dentitions can be associated only with themselves and not with any other dentition.

If this claim were true, it would indeed be possible to conclude that a dentition found consistent with a mark is the source of that mark. But we know from the substrate problems described, above, and from systematic empirical research as well as observations by practicing forensic dentists that repeated bites by a single set of dentition produce very different bite markings.

The advantage of adopting and asserting the assumption of uniqueness is that it obviates the need to collect, analyse, and employ information about the population distribution of dentitions and bitemark characteristics. Much of the hard work of empirical research can be dispensed with. The problem with the assumption of uniqueness is that it is nothing more than ipse dixit. The NAS Report on forensic science stated:. No thorough study has been conducted of large populations to establish the uniqueness of bite marks; theoretical studies promoting the uniqueness theory include more teeth than are seen in most bite marks submitted for comparison.

There is no central repository of bite marks and patterns. Most comparisons are made between the bite mark and dental casts of an individual or individuals of interest. Rarely are comparisons made between the bite mark and a number of models from other individuals in addition to those of the individual in question. A recent review sought to examine all empirical research aimed at determining whether all human dentition is unique.

None was able to support a conclusion of dental uniqueness. Nine of the studies explicitly failed to find uniqueness. Four claimed to have succeeded, but were found to be methodologically incapable of supporting the asserted conclusions. Four additional studies 80 found specimens in the study populations that were indistinguishable within measurement resolution—that is, their differences did not exceed the margin of error for the study population.

These findings bring the notion of dental uniqueness, central to bitemark analysis, into considerable doubt. As the assumption of uniqueness fades away, so does the claim that bitemark comparison can dependably link a bite mark to its source. In light of these developments, the ABFO has recently backed away from the theory of uniqueness and the associated notion of identification-to-the-exclusion-of-all-others. Forensic dentists then need only distinguish among the dentition of a handful of known people, not speculate about tens of millions of unknown dentitions.

The empirical research described in this section is noteworthy, first, for how little of it there is and, second, for how much of what does exist refutes the claims of forensic dentists regarding their ability to identify the source of a bite mark. False-negative errors could occur for many reasons—some pertaining to the circumstances of the bite and the substrate receiving the bite, some pertaining to the medium the examiner is using to visualize the questioned and known patterns eg photographs under different lighting conditions , others pertaining to the decision-making machinery of the examiners.

Careful research would need to be designed in order to isolate the various possible causes of the errors and to try to develop ways to reduce errors stemming from those causes. Similarly, false-positive errors could occur for a variety of reasons, pertaining to different aspects of the bite sources, tools for and conditions of visualizing the bite marks, or the perceptual and decision characteristics of examiners.

Intraexaminer or within-examiner unreliability refers to the same examiner giving different answers on different occasions when examining the very same evidence. Interexaminer or between-examiner unreliability refers to different examiners examining the same evidence and reaching different conclusions about it.

Reliability concerns only consistency of measurement. It does not address whether a measurement is correct. Five forensic dentists might all agree on whether or not a suspect's dentition made a bite mark high reliability , but they might all be incorrect low validity. The ABFO recently sponsored and conducted a reliability study of the judgements of experienced, board-certified forensic dentists making very basic decisions about bite marks.

The 38 examiners were asked to review the injuries in each of the photographs and respond to three very basic questions. As will become apparent, the greater the degree of agreement among the examiners, the more reliability is indicated that is, repeatability of judgements by different examiners , and the lower the rate of agreement, the less reliable their judgements are. No one can know which answers were right or wrong that is, this was not a test of validity. We can know only the extent to which they agreed or disagreed with each other.

Question 1: Is there sufficient evidence in the presented materials to render an opinion on whether the patterned injury is a human bite mark?

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Findings: for only 4 of the cases, did all examiners agree on whether an opinion could be reached on whether an injury was a bite mark or not. For half of the cases, there was less than 71 per cent agreement. For one quarter of the cases, there was less than 47 per cent agreement. Question 2. Is it a human bite mark, not a human bite mark, or suggestive of a human bite mark? Findings: in about a quarter of the cases, fewer than half of the examiners agreed on whether the injury was or was not a bite mark.

In 71 of the cases, fewer than 70 per cent agreed on whether the injury was a bite mark. Question 3. Does the bite mark have distinct, identifiable arches and individual tooth marks? By the time they reached Question 3, the examiners were already widely divided from each other in their opinions. Those who did not think that the injury photograph contained enough information to make a decision did not opine on whether it was or was not a bite mark. Those who did not think that the injury was a human bite mark would not be addressing whether individual tooth marks were identifiable.

Taking all three questions together, for just under half of the cases, half or fewer of the examiners agreed on the same trio of responses. For only 14 of the cases, did at least 80 per cent of the examiners agree on the trio of responses. Although no one knows which answers of which examiners were correct or not the validity question , one can be sure that many answers were incorrect since contradictory answers cannot all be correct.

The reliability of a measuring instrument sets an upper limit on its possible validity. Put simply, if dental examiners cannot agree on whether or not there is enough information in an injury to determine whether it is a bite mark, and cannot agree on whether or not a wound is a bite mark, then there is nothing more they can be relied upon to say.

Unless and until they can do this threshold task dependably, there is no other aspect of bitemark identification that can be counted upon to produce dependable conclusions. Over the approximately four decades in which forensic dentists have been testifying in courts claiming the ability to accurately identify the individuals who were the sources of bite marks, remarkably few tests have been carried out to assess their accuracy.

While there have been hundreds of studies of eyewitness accuracy, and many dozens of proficiency tests of forensic examiners in other fields, forensic dentists have been tested only a handful of times. Such tests as exist present practitioners with bite marks to compare under circumstances where those conducting the study know which answers are correct and which are incorrect.

The earliest of these tests were conducted in the mids by forensic dentist David Whittaker. Note that pigskin is a more stable material for recording and retaining a bite mark than living human skin, so that tests using pigskin as the substrate would likely overstate the accuracy obtained by bitemark examiners. Incorrect identifications of the bites made in the Whittaker study ranged from 24 per cent under ideal conditions to 91 per cent when identifications were made from photographs taken 24 hours after the bites were made which is more typical of how bitemark comparisons are done.

Only the workshop results have been made public.

Three consisted of materials from actual cases in which the biter's identity was established by independent means , and the fourth was a bite into cheese. Each of those bite marks was compared to what in effect was a lineup of seven bites. Overall, examiners were in error on nearly half of their responses, more of those being false-positive errors identifying a non-biter as being the biter than false negatives failing to identify the actual biter.

False-positive responses affirmatively linking a bite to a person who had not made the bite averaged They designed a biting machine to inflict bites that could be fitted with various cast dentitions from their reference collection, and proceeded to apply multiple bites from the same and different dentitions to different areas of cadaveric skin. They then analysed the resulting bite marks and compared them to the dentitions in their collection, using digitized modeling and various statistical techniques.

The first major finding was that, due to the anisotropic 93 properties of skin, no two bite marks inflicted by the same dentition appeared the same. These findings suggest that accurate source attributions that is, determining which dentition made which bite , is likely to require the bites to have been in more stable substrates such as wax or cheese. The degree of distortion found in the marks on skin was such that even large variations in tooth arrangements did not faithfully transfer, making profiling prediction of dental characteristics unreliable. To better understand the implications of this line of work, it is helpful to keep in mind the range of possible substrates.

That material is designed to receive and hold impressions of teeth with a high degree of accuracy and stability. There is nothing better for the purpose. At the other extreme are elastic and unstable substances that cannot capture details and that subsequently change shape, distorting the tooth impression as they do.

Skin, as a substrate, is closer to the latter extreme. The research described above used cadavers. Because the skin of cadavers lacks the vital response, and does not undergo the changes caused by inflammatory reactions—while most bite marks encountered by courts have been imposed on living victims—it is important to appreciate that the substrate used in the research is more stable, closer to the dental office material end of the spectrum than living flesh is. Moreover, it did so under more controlled conditions, preventing the distortion and slippage due to movement that occurs in a criminal struggle.

The scientific community, and society generally, expects that before being offered to courts, and before courts grant broad and unqualified admission, the claims for a field's techniques will have been validated. Moreover, recent reviews of the field's claims, as well as recent empirical findings, have underscored the lack of reliability and validity of the most fundamental claims about the ability of forensic dentists to identify the source of bite marks on human skin.

The claims of forensic dentistry have for decades outrun empirical testing of those claims.

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Rather than confirming the field's claims, recent research, described in this article, has confirmed that the foundations of bitemark identification are unsound. The rise and coming fall of bitemark evidence has left a trail of miscarriages of justice in its path. A series of individuals have been exonerated by DNA testing in cases involving bitemark evidence and still more have been exonerated by non-DNA evidence. Some of those individuals spent years or even decades in prison. The trial judges who uncritically accepted that bitemark evidence, and the appellate judges and federal habeas judges who did the same, have now had their own judgment called into question.

The opinions that rubberstamped the use of such flimsy evidence now stand as a warning to future judges that they must actually endeavor to carefully apply the law's gatekeeping criteria in criminal cases, and not simply grandfather in the evidence by citing to old opinions that themselves did not apply meaningful scrutiny. If evidence as unreliable as bitemark evidence could go unquestioned in the courts and unsupported by research from the scientific community, what does that say about the larger field of forensics?

Clearly, far more work needs to be done to improve judicial review and scientific research. It has taken more than three decades to begin to undo the massively unsupported field of bitemark evidence. Other fields, such as voiceprint identification and comparative bullet-lead analysis, did rise and fall more quickly. A wide range of forensic disciplines, however, continue to be used, despite questions about their validity. The FBI and a series of crime labs have only recently begun to examine old cases involving, for example, the use of microscopic hair comparisons.

Many observers, including the National Academy of Sciences in its report, have called for a systemic renewal of such legal and scientific efforts and progress has been slow. The rise and impending fall of bitemark evidence powerfully illustrates the costs of the failure to assure that what enters our criminal courts is sound science. Michael J. Saks, Ph. He also is an affiliated faculty member at the University of Haifa, Israel.

His research interests include forensic science and the law. His work has earned a number of awards and has been cited in various judicial opinions, including several by the United States Supreme Court. His doctorate is from the Ohio State University and his M. Thomas D. Albright, Ph. His laboratory seeks to understand the brain bases of visual perception, memory and visually-guided behavior.

His doctorate is from Princeton University. Thomas L. Bohan, Ph. His Ph. He has authored books and peer-reviewed papers in the scientific and legal professional literature. Reflecting his interest in forensic science and its admission into evidence, these publications include early commentary on the Daubert decision and an extensive review of the National Academy of Sciences report Strengthening Forensic Science in the United States.

Barbara E. Bierer, M. She directs the Multi-Regional Clinical Trials Center of the BWH and Harvard, a University-wide effort to improve standards for the planning and conduct of international clinical trials. She has authored or co-authored over publications. Her B. Michael Bowers, D. Over many years he has collaborated with notable legal and forensic dental colleagues to improve the methods and results in forensic identification.

His accompanying intent has been to inform the criminal justice system about bitemark identifiers' scientifically unsubstantiated and dangerous claims of certainty and reliability. Some of his empirical studies and reporting in published peer reviewed books and articles on this subject were cited in the NAS report as a partial basis for its bitemark findings. Mary A. Bush, D. She is on the editorial board of the Journal of Forensic Sciences , has published numerous articles, has contributed to various textbooks, and lectures widely on the topic of forensic odontology including an invited presentation at a congressional hearing.

Peter J. He has worked in many scientific areas, including Forensic Odontology. He has published over 60 articles and his work is referenced in numerous sources including the NASA website. Arturo Casadevall, M. He received his graduate degrees from New York University. Subsequently, he completed internship and residency in internal medicine at Bellevue Hospital. He has authored over scientific papers. He also serves on the National Commission on Forensic Science. Simon A. Cole, Ph. He is co-editor of the journal, Theoretical Criminology. He received his doctorate from Cornell University.

Bonner Denton, Ph. He is recognized as a world leader in scientific optical imaging and development of new analytical instrumentation.

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He received his doctorate in from the University of Illinois. Shari Seidman Diamond, J. She is also a research professor at the American Bar Foundation. She has published more than a hundred articles on legal decision-making in law reviews and behavioral science journals. She was elected to the American Academy of Arts and Sciences. Her publications have been cited by federal and state courts, including the U.

Supreme Court. Rachel Dioso-Villa, Ph. Her research investigates the admissibility of the forensic sciences, the validation of forensic science techniques, specifically fire investigation expertise, and the causes and correlates of wrongful conviction. Jules Epstein, JD. He has lectured on forensics to judges and attorneys. David Faigman, J. His graduate degrees are from the University of Virginia.

He writes in the areas of science and the law, and constitutional law. He has published numerous books and articles concerning the use, or failure to use, scientific research in legal decision-making. He served on the National Academies of Science panel investigating the scientific validity of the polygraph. Lisa Faigman, J. Her areas of expertise include scientific evidence and expert testimony, the integration of science and statistics with law and public policy, forensic evidence, and individual and public health decision-making.

She has a special interest in women's health, neuroscience, and aging. Stephen E. Fienberg, Ph. He is the author or editor of over 25 books and papers and related publications, several of which deal with forensic statistics topics. Brandon L.

Garrett, J. His research and teaching interests include criminal procedure, wrongful convictions, habeas corpus, corporate crime, scientific evidence, and constitutional law. His recent research includes studies of DNA exonerations and organizational prosecutions. Pierre N. Leval of the U. Paul C. Giannelli, J. He received his J. His other degrees include an LL. Other articles have been published in specialty journals at Northwestern, Georgetown, Texas, and N.

  • ACS Distinguished Service Award.
  • Forensic bitemark identification: weak foundations, exaggerated claims.
  • Forensic Analysis: Weighing Bullet Lead Evidence.

His work has been cited in nearly judicial opinions throughout this country including seven decisions of the U. Supreme Court , as well as in foreign courts. In addition, he has testified before the U. Henry T. Greely, J. He specializes in ethical, legal, and social issues arising from the biosciences.

In he was elected a fellow of the American Association for the Advancement of Science. Edward Imwinkelried, J. He is the coauthor of Scientific Evidence 5th ed. He is a contributing editor on scientific evidence to Criminal Law Bulletin and was formerly the expert testimony columnist for National Law Journal. Allan Jamieson, Ph. His doctorate is from Strathclyde University. Karen Kafadar, Ph. She received her Ph. Her research focuses on robust methods, exploratory data analysis, and characterization of uncertainty in the physical, chemical, biological, and engineering sciences.

Jerome P. Kassirer, M. He was editor-in-chief of the New England Journal of Medicine between — He has studied the process of diagnosis for 37 years and is author of numerous scientific papers and review articles on diagnostic reasoning and diagnostic testing and is co-author of Learning Clinical Reasoning He is co-editor of the most recent edition of the Reference Manual on Scientific Evidence , the data source for federal judges, and has published concerning how information is assessed by the courts.

He conducts research in how people reason with forensic and quantitative evidence in legal cases. He teaches classes in statistics and probability, forensic science, decision making, and evidence.