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Development of a Quantifiable Confirmatory Test to Detect Fly Artifacts Contaminating Bloodstain Evidence

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Description of original award (Fiscal Year 2016, $154,521)

As submitted by the proposer: Presently there are no methodologies for distinguishing contaminating insect artifacts produced by flies or other insects that visit and feed on a corpse from stains derived from human body fluids. In fact, artifacts derived from common flies are indistinguishable from bloodstains, particularly those associated with high impact or projected blood spatter. Traditional presumptive chemical tests for blood yield positive results for both blood and insect artifacts, or in some cases (i.e., Hemastix®) provide false positives. DNA typing is also not effective for discrimination since the blood meal contains DNA from the victim, and hence both fly artifacts and bloodstains will display the same genetic profile. Semi-quantifiable morphological measures, as well as alternate lighting methods, have been proposed for identifying certain fly spots from bloodstains, but the methodology is not satisfactory because it is not reliable, is not suitable for all fly species, does not make a distinction from other forms of body fluids that may also be present, and in the case of artifact morphology, is dependent on a very small pool of forensic experts. The lack of diagnostic tests for the identification of insect artifacts at a crime scene means that only subjective interpretation is used to distinguish fly evidence from bloodstains. Insufficient data and methodology are available to make consistently reliable and quantifiable distinctions between insect artifacts and stains from human body fluids. The overall goal of this research program is to develop a rapid, quantifiable, and confirmatory method for distinguishing insect artifacts (i.e., regurgitation and feces) created by fly activity at crime scenes from human body fluids. During the grant period, we propose to accomplish the following objectives: 1) Generation of polyclonal antibodies toward enzymes in artifacts (regurgitation and feces) produced by necrophagous flies; 2) Development of western and dot blot detection of fly enzymes in artifacts produced by necrophagous flies; 3) Characterize specificity of polyclonal antibodies toward artifacts derived from different species of flies common at crime scenes; 4) Determine the potential for polyclonal antibodies to distinguish fly artifacts from human body fluids, including blood, saliva, semen and urine, and assess length of antibody viability in fluid detection; 5) Evaluate the utility of polyclonal antibodies in detection of fly artifacts from a range of household materials, including different floor coverings (carpet types, ceramic and vinyl tiles, wood), wall materials, and furniture fabrics. Note: This project contains a research and/or development component, as defined in applicable law. ca/ncf
Date Created: September 15, 2016