Rethinking the Probative Value of Evidence: Base Rates,Intuitive Profiling,and the “Postdiction” of Behavior

It is argued that American courts may be routinely admitting evidence with little to no probative value and great potential for prejudicial impact. This may be particularly likely with regard to what is essentially intuitive profiling or stereotype related evidence, defined herein as evidence suggesting that the defendant (or other party), or his (her) behavior, fits intuitive profiles (or stereotypes) of the type of person likely to commit the crime or behavior in question. In other words, intuitive profiling evidence is admitted to postdict behavior. Formal empirically based profiling evidence (testimony regarding the fit of a defendant's characteristics or behaviors to formal or scientific profiles of the typical perpetrator of the crime in question for use to prove guilt is inadmissible in American courts. However, we suggest that everyday use of informal intuitive profiles underlies both judicial determinations of probative value diagnosticity, and thus admissibility, of evidence, and jurors' use of the evidence in determining guilt. Demonstrations of the use of base rate information to evaluate the probative value of such intuitive profiling evidence both as evidence of guilt and as evidence of innocence are provided. Demonstrations of both how to evaluate the actual probative value of evidence (when all necessary values are known), and the theoretical limit of its probative value (in circumstances where some values are not known) are provided. It is argued that such evaluations may provide the basis for (1) support of motions to either admit or to exclude evidence, (2) testimony to the jury to help them weigh or interpret evidence, (3) exculpatory profiling (profiling evidence of innocence), (4) pretrial research to establish probative versus prejudicial value of evidence, and (5) sufficiency analyses to determine maximum likelihood of guilt, given multiple items of evidence. Among these, the first two are considered most important, as it can be demonstrated that many profiling characteristics currently admitted in trial (such as evidence of battery to support a murder charge) are not probative of guilt.     

Suicide by self-immolation in Durban,South Africa: a five-year retrospective review

Self-immolation is an uncommon method of suicide, and its occurrence in South Africa is thus far unknown. This study aimed to determine the prevalence of self-immolation deaths and to establish a profile of these cases and the circumstances under which this condition occurs. A 5-year (1996-2000) retrospective review at a mortuary in Durban, South Africa, was conducted. Data were obtained from the Department of Forensic Medicine, the Medical Research Council's National Injury Mortality Surveillance System, and police and hospital records. During the study period, there were 12339 nonnatural deaths, of which 696 (5.6%) were suicides. Self-immolation accounted for 69 (0.6%) of all nonnatural deaths and 69 (9.9%) of all suicides. The subjects had a mean age of 31.2 years and were predominantly female (76.8%) and black (81.2%). The mean burn surface area was 63.3%, and the mean injury severity score was 36.9. Accelerant use was documented in 53 (76.8%) of cases, and paraffin was preferred. All cases occurred indoors. The proportion of suicides due to self-immolation in our study is excessive when compared with international studies that report figures between 0.9% and 2.2% of suicides. Additional studies are necessary to further elucidate the reasons for this discrepancy.     

Detection of ketosis in vitreous at autopsy after embalming

Ketosis occurs in ketoacidosis or malnourishment. When either is suspected in relation to a death, it may be important to analyze for ketosis at autopsy. We encountered a case where starvation was suspected in a deceased nursing home resident, where the body had been embalmed prior to autopsy. Gas chromatography (GC) was unable to separate acetone from formaldehyde, a component of embalming fluid. The Acetest is a simple test that can detect acetone and acetoacetate in body fluids. We validated the Acetest with GC on vitreous. The Acetest and GC were consistent except at very low levels of acetone or acetoacetate. The sensitivity of the Acetest for acetoacetate in vitreous was 10 mg/dL, consistent with early starvation. Significant interference from embalming fluid did not occur. The Acetest was negative in the described case. The Acetest is a simple and useful test for the detection of ketosis in embalmed autopsies.     

A more sensitive method for the quantitation of genomic DNA by Alu amplification

Current procedures for human DNA quantitation reach their limit at 150 pg DNA, which is above the limit of the PCR profiling range using Profiler-Plus (Applied Biosystems, CA). This study tested the potential for the use of primate specific Alu sequences in forensic science for the sensitive detection and quantitaion of DNA. A fluorescently labelled primer pair was designed enabling high efficiency amplification of the core Alu sequence within primate DNA. Quantitation was performed by measurement of fluorescence intensity and comparison to a series of standard template DNA amounts via the construction of a standard curve. The new Alu-based quantitation protocol developed has shown its feasibility in more sensitively quantitating (100-2.5 pg) unknown amounts of human DNA for forensic use. The method is compatible with the use and throughput of current forensic procedures.     

Evaluation of some oxygen, sulfur, and selenium substituted ninhydrin analogues, nitrophenylninhydrin and benzo[f]furoninhydrin

Six ninhydrin analogues containing oxygen, sulfur, and selenium substituents at the C-5 position, 5-(4-nitrophenyl)ninhydrin, and benzo[f]furoninhydrin were evaluated as fingerprint development reagents. The analogues all showed good fingerprint color development but were not superior to ninhydrin in this respect. The benzo[f]furoninhydrin complex was strongly luminescent at room temperature following zinc complexation, while the remaining analogues required cooling to -196 degrees C to produce optimum luminescence. The benzo[f]furo, nitrophenyl, and methyl selenide analogues showed the best potential as fingerprint reagents with the benzo[f]furo analogue comparing favorably with DFO.     

Brain acetaldehyde and ethanol: method of determination and diagnostic significance in ethanol poisoning

The content of ethanol and acetaldehyde in the limbic cortex and reticular formation of the brain was measured by gas-liquid chromatography in lethal ethanol poisoning. The content of acetaldehyde was significantly increased in the gyrus cinguli of the brain. Lethal poisonings occurred during any stage of ethanol intoxication. The data characterizing individual ethanol tolerance were obtained, which can be used for differential diagnosis of ethanol poisoning in practical forensic medicine.     

A method for group identification of hair infected with Microsporum

A method for identifying the group appurtenance of biological objects from subjects suffering from various diseases is developed. The method can be used in examination of putrefactive objects (blood, secretions, hair, etc.) and in cases when the group appurtenance cannot be identified by other methods.     

Antigenic differentiation of blood stains by the Lewis system in practical forensic medical expert evaluation

A modification of quantitative absorption and absorption elution tests with blood stain washing before the absorption phase is presented. Due to washing, the effect of carrier object on anti-Le(a) and anti-Le(b) sera is decreased and the sensitivity of the method is increased. Additional adsorption of the sera and elution into test erythrocytes treated with protease C is suggested for increasing the number of standard sera fit for the absorption-elution test. A new technology for preparing anti-Le(a) and anti-Le(b) immunoreagents is described.