fsci 632 module 7 concept application

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Stevenson University *

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Chemistry

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Jan 9, 2024

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Name: Tianna Fulmore Date: 12/6/23 Pattern Analysis Module 7: Bloodstain Pattern Analysis Concept Application 1. Below are several bloodstains. For each bloodstain, determine the Angle of Impact by completing the chart. Measure the bloodstain in millimeters (mm), you can either do this by printing the worksheet or measuring directly on your computer screen. Bloodstain Width of bloodstain (mm) Length of bloodstain (mm) Angle of Impact 15 mm 33 mm 27.04 degrees 23 mm 33 mm 44.18 degrees 8 mm 37 mm 12.49 degrees 5 mm 33 mm 8.71 degrees 25 mm 40 mm 38.68 degrees

Name: Tianna Fulmore Date: 12/6/23 2. The Precipitin Test is frequently used when blood plays a part in a crime scene. What is this test? How does it work? And why is it useful to those in Pattern Analysis? Be sure to cite your source(s). The Precipitin Reaction “describes the Precipitin test as being a test used by forensic scientists to identify the species of a blood sample using the characteristics of proteins” (The Precipitin Reaction, 1912). Therefore, is also another technique for the Precipitin test: “An ordinary Pasteur pipette is used with its capillary end closed. The desired number of pipettes is placed in a rack. The capillary ends of these tubes are fixed in suitable grooves in the lower part of the rack. One drop or less of the anti-serum is run along the upper inner surface. The anti-serum finally settles at the top of capillary portion of the tub leaving below it an air column. One drop or less of the stain extract is now added. This forms a distinct upper layer on the surface of the anti-serum. The reading is carried out by daylight against a black background. Any light coming through the rack is eliminated by a piece of black paper fixed on the side of the rack facing the examiner. The light coming through the X-ray viewer hits the air column in the capillary portion of the pipette, and by reflection the two fluids are illuminated in an upward direction. The well- known ring at the line of contact between the two fluids is clearly shown in positive reactions” (Kayssi, 1950). However, an alternative method is used by serologists to determine if an individual's blood sample has human origins.: “(1) An animal is injected with human blood and forms antibodies, (2) the antibodies are harvested from the animal's blood serum (3) in a test tube, an extract from the suspected bloodstain is added to the antiserum, and (4) if a precipitate forms where the two meet, then it is human blood” (Forensic Serology, n.d.). Forensics uses pattern analysis to establish biological relationships and to identify a blood sample's origin and species. References: Kayssi, A. I. (1950). A simple technique for the precipitin test. Journal of Criminal Law and Criminology, 40(4). Retrieved from https://scholarlycommons.law.northwestern.edu/cgi/viewcontent.cgi? article=3710&context=jclc . The Precipitin Reaction. (1912). Nature 88, 566. https://doi.org/10.1038/088566a0 Forensic Serology. (n.d.). San José State University. Retrieved from https://www.sjsu.edu/people/mary.juno/courses/1066/s7/ForensicSerology.pdf

Name: Tianna Fulmore Date: 12/6/23 3. The following is a FAKE crime scene created for the purpose of this class; the two pictures are different viewpoints from the scene. Answer the following questions: a. What would you guess the angle of impact is of the blood drop circled in green on the picture? - There is certainly less than a 90-degree angle in the angle of impact of this blood spatter. Because the spatter has an elongated shape instead of an elliptical one, I would say that the angle of impact is somewhere between 20 degrees and 30 degrees. It would probably be around 25 degrees. The wipe pattern in the picture should be surrounded by purple boxes, and the castoff pattern should be surrounded by blue boxes. b. Place a purple box around the wipe pattern in the picture. c. Place a blue box around a castoff pattern in the picture. d. Is the pooling of blood below the victim’s head a passive bloodstain, a projected bloodstain, or a transfer/contact bloodstain? - In the case of passive bloodstaining, the pooling of blood below the victim's head results from gravity's action. As there was no mist, spurt, or spray

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Name: Tianna Fulmore Date: 12/6/23 created by the blood, it is not a projected bloodstain. There was no contact with a second object, so it is also not a transfer/contact bloodstain.