Forensic Science Graduate Research Projects
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Browsing Forensic Science Graduate Research Projects by Subject "Blood forensics"
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Item Degrees of contrast: Detection of latent bloodstains on fabric using ALS and the effects of washing(2020) James, Matthew E.Bloodstains are a useful piece of evidence for solving many crimes. The DNA analysis of bloodstains deposited on a piece of clothing can identify whose blood is on the clothing and may place a subject at the scene. In some cases, the stain’s shape, and overall pattern, can provide much more information. However, it is particularly difficult to identify bloodstains on dark clothing and clothing with patterns. Current methods to detect these stains include advanced photography techniques with Alternate Light Sources (ALS) or the use of chemicals that react to the hemoglobin and fluoresce. Photography methods are non-invasive, but there is little research on what wavelengths are the most effective. Chemicals such as Luminol, Bluestar, and Fluorescein are effective, but ultimately ruin the pattern and prevent morphology interpretation of the stain. This study explores the use of ALS to photograph bloodstains in order to provide an alternative non-invasive tool before the use of chemical detection techniques. This study examined whether blood always absorbed light in the 300nm to 900nm range and the best wavelength for observing blood on dark and or patterned fabrics. It also explored whether fabric type, fabric color, or pattern affected the ability to view blood on fabrics, if washing the fabric affected the use of ALS, and, if so, to what extent. Sixty-nine fabrics were photographed in monochrome under ambient light, and then with and without filter under 350nm - 380nm (UV), 400nm - 430nm (Violet), 430nm - 480nm (Blue), 480nm - 560nm (Green), and 800nm - 900nm (Infrared) light. Each photograph was bracketed to ensure the best exposure and contrast between the stain and fabric. In total, 33 photographs were taken for each fabric after each wash cycle. Contrast was measured between the bloodstain and the fabric using ImageJ software to measure the effectiveness of each wavelength. Results indicated photography with ALS was a viable method for blood detection on fabrics and should be used prior to chemical means. Further, infrared, followed by violet light with no filter, were the most effective light sources for viewing bloodstains on dark fabrics without the use of chemicals.Item Vanishing Blood Stains: Determining the optimum apparel fabric and residential lighting conditions for a bloodstain to disappear(2020) Sullivan, BrittniBloodstain Pattern Analysis (BPA) is one of the most important forensic crime scene techniques to date. Fluid dynamics with blood remain relatively similar across the board, which is why many researchers remain focused on specific patterns and what they can reveal about the movements of contributors in a scene. As a bloodstain pattern analyst becomes more proficient in the identification of certain stains, the advanced analyst will begin to study the effect of blood on fabrics. It is well known within the field of BPA that Alternate Light Sources (ALS) are required in most scenes containing blood evidence. This researcher sought to identify which specific fabrics (color and composition) best mask blood stains under residential lighting conditions. Determining the fabric which best disguised a given blood stain will prove useful to the Crime Scene Technician (CST) as well as the subsequent litigation team. If a person alleged they observed “bloody clothing” on a subject/victim, this research answered whether this observation was possible to the untrained eye. Additionally, the results sought to determine the optimum fabric type, pattern, and color to best disguise blood on apparel fabric at a scene. When the “optimum fabric” was observed at a given crime scene with potential blood evidence, this research would trigger the crime scene technician to utilize an ALS, as well as submit the item for in-depth analysis at the laboratory. A sample of fabrics was tested using recent statistics of U.S. consumption of fabric. This ensured an equal sampling of the general American population, and included various solid color and printed fabrics. Additionally, the sample fabrics included various military uniforms (Army Multicam, Marine Combat Utility Uniform, Navy Working Uniform, and Airman Battle Uniform) to make the study relevant to the Department of Defense. The various fabric types and patterns provided different qualities with the respective blood stains that were subsequently measured to gain quantitative results. The fabric samples were placed in four separate indoor lighting conditions, and the contrast of the stains were objectively measured and determined there was no significant difference between each light source. This research ultimately determined there was a significant difference between the construction and color of the fabric.