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Results Several scores were calculated for each method. The detection rate of latent stains (Figure 1) was calculated based on the visibility of latent.

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Presentation on theme: "Results Several scores were calculated for each method. The detection rate of latent stains (Figure 1) was calculated based on the visibility of latent."— Presentation transcript:

1 Results Several scores were calculated for each method. The detection rate of latent stains (Figure 1) was calculated based on the visibility of latent stains after the application of each method. Any score higher than 0 indicated that bloodstains were detected. The average visibility score of the latent stains was also determined using the 0-3 scale (Figure 2). Finally, the improvement in visibility was calculated by subtracting the initial score (from the initial visible light photo) from the final score (after the application of the method). References 1. Adair T. Experimental detection of blood under painted surfaces. Int. Assoc. Bloodstain Pattern Analysts, Mar. 2006: Bily C, Maldonado H. The application of luminol to bloodstains concealed by multiple layers of paint. J Forensic Ident. 2006; 56 (6): Farrar A, Porter G, Renshaw A. Detection of latent bloodstains beneath painted surfaces using reflected infrared photography. J Forensic Sci. 2012; 57 (5): Lin C A, et al. Forensic applications of infrared imaging for the detection and recording of latent evidence. J Forensic Sci. 2007; 52 (5): Howard M, Nessan M. Detecting bloodstains under multiple layers of paint. J For Ident. 2010; 60 (6): Materials and Methods Blood stains (impact spatter, transfer, and pattern) were applied to sections of wood paneling and primed/painted drywall. White and black paint was used to conceal blood on both drywall and wood in thicknesses up to 4 layers. Various methods were tested for detection and documentation of the blood. Methods were also tested for removal of the paint layers. Detection and documentation methods tested:Paint removal methods: -Infrared (IR) photography - sanding sponge -Ultraviolet light (UV) photography - Citristrip ® chemical paint stripper -Alternate light source (ALS) photography -leucocrystal violet (LCV) -amido black -Luminol Photographs were taken after each layer of paint was applied and after the application of each method. A visual examination was performed on the photographs to determine if and when the bloodstains became visible with each method. The visibility of the stains was rated using a scoring system: 0: bloodstain not visible 1: partial bloodstain visible; no pattern recognized 2: 1-2 bloodstain patterns visible and identifiable 3: all bloodstain patterns visible and identifiable Visible light documentation of suspected area (Figures 3 and 4) Search with ALS (475 nm) and orange goggles or with IR-converted camera in live preview mode Apply luminol (Figures 5 and 6) Remove paint with sanding sponges or Citristrip® ALS photography (475 nm, orange filter) for white paint or IR photography for black paint (Figure 7) Apply hydrogen peroxide to stains under dark paint (Figure 8) This entire procedure could be implemented quickly and easily as it requires chemicals, procedures, and equipment that are commonly used in most laboratories. Further testing should be done to assess the value of this method when used with other paint colors and substrates. Also, the sensitivity of this method should be tested using diluted or cleaned bloodstains. Kate Timmons, BA; Jessica Van Ackeren*, BS; Catherine G Rushton, MSFS; Pamela Staton, PhD Figure 1. Of the detection methods tested, the application of luminol resulted in the highest detection rate (100%) of bloodstains concealed by paint. Detection and Documentation of Bloodstains Concealed by Paint: A Practical Approach Marshall University Forensic Science Center, 1401 Forensic Science Dr., Huntington, WV 25701; *Johnson County Sheriff’s Office Criminalistics Laboratory, S. Sunset Drive Olathe, KS Introduction Blood evidence at a crime scene can have significant value in an investigation as both a source of genetic material and a tool for event reconstruction. One method of concealing bloodstain evidence is to paint the surface on which it was deposited. 1 Recent research has indicated that there are several methods including luminol, infrared photography, and alternate light sources that can be used to detect blood under paint. 2, 3, 4 Paint removal methods have also been effective at revealing concealed bloodstain patterns. 5 Acknowledgements This study was made possible by the Johnson County, KS Sheriff’s Office Criminalistics Laboratory, specifically the Crime Scene Investigation Unit, under the supervision of Ryan Rezelle and Jessica Van Ackeren. The author also recognizes Kelli Lippold, BS, for her assistance in this experiment. Abstract The purpose of this study was to determine the best process for detection and documentation of bloodstains obscured by paint. The best detection method was the application of luminol which allowed for 100% detection of blood through 4 layers of paint. After detection, manual paint removal using sanding sponges followed by ALS photography, for surfaces painted white, or IR photography, for surfaces painted black, was the best method to visualize and document the stains. This process allowed for detection, documentation, and presumptive testing of bloodstains on all samples tested. Figure 2. Paint removal by sanding followed by ALS (white paint) or IR (black paint) photography resulted in the best visibility of latent stains (1.75) and the highest average improvement in visibility of all stains (1.21). Discussion With 100% detection of concealed stains, luminol had the highest rate of detection. Removal of the paint by sanding followed by ALS or IR photography resulted in the best visibility of latent stains with a score of This method also gave the highest average improvement in the visibility of all stains at To further visualize the stains, LCV was applied to the bloodstains under black paint. Though the blood stained purple, some bloodstain patterns were visible due to the white foam formed in the reaction with the 3% hydrogen peroxide in the LCV kit. For a stronger reaction to visualize more bloodstains, undiluted hydrogen peroxide was applied. This revealed all aspects of the previously latent bloodstains on both substrates. Conclusions The purpose of this study was to identify the best process for investigators to use when it is suspected that bloodstains may be present under paint. This experiment demonstrated that it is possible to not only detect blood concealed by paint, but also to document the bloodstain pattern. Additionally, the paint can be removed to facilitate swabbing for further forensic testing. An effective procedure is: Figure 5. Bloodstains under 4 layers of white paint after treatment with luminol. Drywall – White Paint Wood – White Paint Figure 3. Visible light photography of initial bloodstains. Figure 7. ALS photographs of bloodstains under white paint after treatment with luminol and paint removal by sanding. Drywall – White Paint Wood – White Paint Figure 8. Visible light photographs of bloodstains under black paint after treatment with luminol, paint removal by sanding, application of LCV, and application of undiluted hydrogen peroxide. Drywall – Black Paint Wood – Black Paint Figure 4. Visible light photography of initial bloodstains. Figure 6. Bloodstains under 4 layers of paint after treatment with luminol. Drywall – Black Paint Wood – Black Paint


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