15.1 Forensic Murder Mystery Lab Police are called to a house where they discover a body...

 

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15.1 Forensic Murder Mystery Lab Police are called to a house where they discover a body near the back door. There is a fresh pool of blood near the victim's head. Officers question the neighbors and learn that a plumber and an electrician made service calls to the house just hours before. They are able to trace both. They recover a shirt with dark stains from the service van of the plumber and rags with similar dark stains from the electrician's van. Your forensics lab receives the following items to test: Sample 1: Stained cloth from the plumber's van. Sample 2: Stained cloth from the electrician's van. Sample 3: Blood collected from under the victim's head. First, test the shirt and rags to determine if the stains are caused by blood. Go to your workstation and place a drop of phenolphthalein/peroxide solution on each stain. A purple-violet color reaction indicates that blood may be present. The absence of this reaction indicates that blood is not present. Record your results. Color reaction from Sample 1: Color reaction from Sample 2: Based on the results of this test, which person, the plumber or the electrician, becomes your chief suspect? When confronted, your chief suspect claims to have had a nosebleed, thus account- ing for the blood stain. Investigators have now been able to recover a blood sample (Sample 4) from the suspect's van. It is suitable for blood-typing. You ask for and receive a blood sample from the suspect (Sample 5). Proceed as follows to type your 3 blood samples: 1. Using the dropper vial, place a drop of Sample 3 (victim's blood) in each well of the blood-typing slide. Replace the cap on the dropper vial. 2. Add a drop of synthetic anti-A (blue) to the well labeled A. Replace the cap. 3. Add a drop of synthetic anti-B serum (yellow) to the well labeled B. Replace the cap. 4. Add a drop of synthetic anti-Rh serum (clear) to the well labeled Rh. Replace the cap. 5. Using a different-color mixing stick for each well (blue for anti-A, yellow for anti-B, white for anti-Rh), gently stir the synthetic blood and anti-serum drops for 30 seconds. Discard each stick after a single use to avoid contamination. 15.1 Forensic Murder Mystery Lab Police are called to a house where they discover a body near the back door. There is a fresh pool of blood near the victim's head. Officers question the neighbors and learn that a plumber and an electrician made service calls to the house just hours before. They are able to trace both. They recover a shirt with dark stains from the service van of the plumber and rags with similar dark stains from the electrician's van. Your forensics lab receives the following items to test: Sample 1: Stained cloth from the plumber's van. Sample 2: Stained cloth from the electrician's van. Sample 3: Blood collected from under the victim's head. First, test the shirt and rags to determine if the stains are caused by blood. Go to your workstation and place a drop of phenolphthalein/peroxide solution on each stain. A purple-violet color reaction indicates that blood may be present. The absence of this reaction indicates that blood is not present. Record your results. Color reaction from Sample 1: Color reaction from Sample 2: Based on the results of this test, which person, the plumber or the electrician, becomes your chief suspect? When confronted, your chief suspect claims to have had a nosebleed, thus account- ing for the blood stain. Investigators have now been able to recover a blood sample (Sample 4) from the suspect's van. It is suitable for blood-typing. You ask for and receive a blood sample from the suspect (Sample 5). Proceed as follows to type your 3 blood samples: 1. Using the dropper vial, place a drop of Sample 3 (victim's blood) in each well of the blood-typing slide. Replace the cap on the dropper vial. 2. Add a drop of synthetic anti-A (blue) to the well labeled A. Replace the cap. 3. Add a drop of synthetic anti-B serum (yellow) to the well labeled B. Replace the cap. 4. Add a drop of synthetic anti-Rh serum (clear) to the well labeled Rh. Replace the cap. 5. Using a different-color mixing stick for each well (blue for anti-A, yellow for anti-B, white for anti-Rh), gently stir the synthetic blood and anti-serum drops for 30 seconds. Discard each stick after a single use to avoid contamination.

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Phenolphthalein test is used to determine the presence of bl... View the full answer