Difference between revisions of "Unvalidated or Improper Forensic Science"

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c) The examiner may be able to determine the age and sex of the individual- The age of an individual cannot be determined definitively, however, the microscopic appearance of certain human hairs, such as those of infants and elderly individuals, may provide a general indication of age. The hairs of infants, for example, are generally finer and less distinctive in microscopic appearance. As individuals age, hair can undergo pigment loss and changes in the configuration of the hair shaft to become much finer and more variable in diameter. Although the sex of an individual is difficult to determine from microscopic examination, longer, treated hairs are more frequently encountered in female individuals. Sex can be determined from a forcibly removed hair (with tissue), but this is not routinely done.
 
c) The examiner may be able to determine the age and sex of the individual- The age of an individual cannot be determined definitively, however, the microscopic appearance of certain human hairs, such as those of infants and elderly individuals, may provide a general indication of age. The hairs of infants, for example, are generally finer and less distinctive in microscopic appearance. As individuals age, hair can undergo pigment loss and changes in the configuration of the hair shaft to become much finer and more variable in diameter. Although the sex of an individual is difficult to determine from microscopic examination, longer, treated hairs are more frequently encountered in female individuals. Sex can be determined from a forcibly removed hair (with tissue), but this is not routinely done.
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===Data of erroneous hair microscopy===
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Hair microscopy is not 100% accurate. Forensic hair evidence has increasingly been scrutinized due to studies indicating high error rates.
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As the FBI noted in its 1984 handbook, microscopic hair examination is "not positive evidence."
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(For further information see Fed. Bureau of Investigation, Handbook of Forensic Science. 33(1984) )
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Furthermore The National Research Council has explained:
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"Although hair examiners can associate a hair with racial characteristics and body source (trunk, head, or pubic area) the variations among hairs on a given person make definitive association of a single hair with an individual problematic. The microscopic comparison of hairs is also subjective and can lead to differences of opinion among equally qualified experts"
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(For further info see Comm. on DNA Tech. in Forensic Sci. Nat'l Research Council, DNA Technology)
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Though there is not, and never has been, any statistical basis for hair comparison, some experts have fabricated frequencies and probabilities based on their own undocumented estimates, rather than any reliable empirical data.
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An example of such a testimony can be seen in the US case of STATE OF MONTANA v. JIMMY RAY BROMGARD.

Revision as of 10:23, 1 June 2010