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Forensic Biology Screening Workshop Case Studies. Case Studies. Blood case – homicide Sex Assault – juvenile Burglary. Case Study #1. Scenario: 37 year old male victim found dead in home Victim found in bedroom Victim was stabbed Broken window = POE No evidence of sex crime.
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Forensic Biology Screening Workshop Case Studies
Case Studies • Blood case – homicide • Sex Assault – juvenile • Burglary
Case Study #1 • Scenario: • 37 year old male victim found dead in home • Victim found in bedroom • Victim was stabbed • Broken window = POE • No evidence of sex crime
Case Study #1 • Evidence sent in for analysis: • Knife from outside back door • Swab of red brown stain at POE • Fingernail scrapings from victim • Victim’s clothing • Swabs from red brown staining throughout house WHAT QUESTIONS WOULD YOU HAVE FOR THE DETECTIVE ON THE CASE PRIOR TO WORKING ON EVIDENCE?
Case Study #1 • What is the best evidence? • How would you screen: • Fingernail scrapings • Knife • Swab from broken window • Victim’s shirt
Case Study #1 • What might be the problem with screening victim’s clothes? • Suspect may or may not be bleeding • Victim was stabbed – a lot of victim blood and possible little suspect blood
Case Study #1 • Stain selection is KEY when you have numerous POSITIVE areas to send on for DNA testing • EXAMPLE: • Case Study #1 • Victim shirt • Several stains • On the back side wearing there are several stains…
Case Study #1 Which stain has best chance of being from the suspect?
Case Study #1 • Results: • Shirt = KM POS • Knife = KM POS • Swab from window = KM NEG • Fingernail scrapings = Swabbed for DNA
Case Study #1 • How would you report your results? • Shirt • Knife • Swab from outside window • Fingernail scrapings
Case Study #2 • Scenario: • 5 year old girl complains of possible sexual assault by male babysitter • Parent’s bring her to hospital within 3 hours of possible attack QUESTIONS FOR DETECTIVE?
Case Study #2 • Upon further information from the detective • Vaginal penetration, unknown if penis or digital • Breasts were touched and possibly licked
Case Study #2 • Evidence collected: • Vaginal swabs • Breast swabs • Oral swabs • Panties • Shirt • Pants WHAT WOULD YOU TEST FIRST?
Case Study #2 • How would you screen? • Vaginal swabs • Breast swabs • Oral swabs • Panties • Shirt • Pants
Case Study #2 • RESULTS: • Vaginal swabs • AP= NEG, MICRO=NEG, AMYLASE=POS • Breast swabs • AMYLASE = NEG • Oral swabs • AP = NEG, MICRO= NEG
Case Study #2 • Panties • AP = NEG, AMYLASE = INCONCLUSIVE • Shirt • AP = NEG • Pants • AP = POS, MICRO = NEG, P30 = POS
Case Study #2 • How would you report your results? • Vag swabs • Breast swabs • Oral swabs • Panties • Shirt • Pants
Case Study #3 • Scenario: • A jewelry store was broken into • Glass door broken = POE • Clerk was hit with butt of gun • Remembers suspect wearing gloves, ski mask, baseball cap
Case Study #3 • Evidence collected for analysis: • 1 white cotton glove • Black ski mask • Baseball cap • Swab of r/b stain at POE QUESTIONS FOR THE DETECTIVE?
Case Study #3 • What tests would you perform on: • Glove • Ski mask • Baseball cap • Swab
Case Study #3 • How would you report your results? • Glove • Ski mask • Baseball cap • Swab