Forensic Biology Screening Workshop Case Studies Case Studies

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, P 30 = 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