The National Institute of Justice guide for eyewitness identification evidence: Can it improve juror decision-making?

Mistaken eyewitness identifications of innocent lead to more false convictions in the United States than any other cause. In response to concerns about the reliability of eyewitness evidence, the National Institute of Justice (NIJ) in 1999 published a Guide for the gathering and preservation of eyewitness evidence by law enforcement personnel. Previous research has shown that eyewitness identifications are more accurate when obtained using procedures recommended in the NIJ Guide. This experiment assessed whether informing jurors about the Guide can improve their ability to discriminate between eyewitness identifications likely to be accurate and those likely to be inaccurate and, if so, how to most effectively provide jurors with such information. ^ Seven hundred sixteen U.S. citizens who reported for criminal jury duty participated. Half of the participant jurors read a summary of an armed robbery trial in which the police followed the NIJ Guide when obtaining an eyewitness identification of the defendant. The other half read about an identical case in which the police did not follow the Guide. Jurors received information about the Guide from a court-appointed expert witness, one of the attorneys in the case, the trial judge, the judge in combination with one of the attorneys, or from no one (in the control groups). Jurors then rendered a verdict in the case and answered questions about the evidence in the case. ^ When an expert witness or the judge (either alone or in combination with one of the attorneys) informed jurors about the Guide, the jurors voted to convict defendants likely to be guilty and to acquit defendants likely to be innocent more often than did uninformed jurors assigned to a control group. These data suggest that informing jurors about the NIJ Guide using expert testimony or instructions from a judge will improve the quality and accuracy of jurors' verdict decisions in cases involving eyewitness identification evidence. However, more research is needed to determine whether the judge will remain an effective source of information about the Guide in a longer, more detailed trial scenario and to learn more about the underlying psychological processes governing the effects observed in this experiment. ^

Variables affecting the collection and preservation of human scent components through instrumental and biological evaluations

In certain European countries and the United States of America, canines have been successfully used in human scent identification. There is however, limited scientific knowledge on the composition of human scent and the detection mechanism that produces an alert from canines. This lack of information has resulted in successful legal challenges to human scent evidence in the courts of law. ^ The main objective of this research was to utilize science to validate the current practices of using human scent evidence in criminal cases. The goals of this study were to utilize Headspace Solid Phase Micro Extraction Gas Chromatography Mass Spectrometry (HS-SPME-GC/MS) to determine the optimum collection and storage conditions for human scent samples, to investigate whether the amount of DNA deposited upon contact with an object affects the alerts produced by human scent identification canines, and to create a prototype pseudo human scent which could be used for training purposes. ^ Hand odor samples which were collected on different sorbent materials and exposed to various environmental conditions showed that human scent samples should be stored without prolonged exposure to UVA/UVB light to allow minimal changes to the overall scent profile. Various methods of collecting human scent from objects were also investigated and it was determined that passive collection methods yields ten times more VOCs by mass than active collection methods. ^ Through the use of polymerase chain reaction (PCR) no correlation was found between the amount of DNA that was deposited upon contact with an object and the alerts that were produced by human scent identification canines. Preliminary studies conducted to create a prototype pseudo human scent showed that it is possible to produce fractions of a human scent sample which can be presented to the canines to determine whether specific fractions or the entire sample is needed to produce alerts by the human scent identification canines. ^

Variables Affecting the Collection and Preservation of Human Scent Components through Instrumental and Biological Evaluations

In certain European countries and the United States of America, canines have been successfully used in human scent identification. There is however, limited scientific knowledge on the composition of human scent and the detection mechanism that produces an alert from canines. This lack of information has resulted in successful legal challenges to human scent evidence in the courts of law. The main objective of this research was to utilize science to validate the current practices of using human scent evidence in criminal cases. The goals of this study were to utilize Headspace Solid Phase Micro Extraction Gas Chromatography Mass Spectrometry (HS-SPME-GC/MS) to determine the optimum collection and storage conditions for human scent samples, to investigate whether the amount of DNA deposited upon contact with an object affects the alerts produced by human scent identification canines, and to create a prototype pseudo human scent which could be used for training purposes. Hand odor samples which were collected on different sorbent materials and exposed to various environmental conditions showed that human scent samples should be stored without prolonged exposure to UVA/UVB light to allow minimal changes to the overall scent profile. Various methods of collecting human scent from objects were also investigated and it was determined that passive collection methods yields ten times more VOCs by mass than active collection methods. Through the use of polymerase chain reaction (PCR) no correlation was found between the amount of DNA that was deposited upon contact with an object and the alerts that were produced by human scent identification canines. Preliminary studies conducted to create a prototype pseudo human scent showed that it is possible to produce fractions of a human scent sample which can be presented to the canines to determine whether specific fractions or the entire sample is needed to produce alerts by the human scent identification canines.