In Depth Post #5

Record a short section of conversation between you and your mentor. Transcribe the conversation. Identify the different hats in the conversation.

The last lecture I went to was on Forensic Biology. This is the study of biological substances, like hair, blood, saliva, and so on. The lecture was an hour and a half, so I will put in sections of my notes that exemplify the different hats.


White hat:

What do we know?

One of the topics Dr. Warren touched on was the study of hair. Here are the notes for this section:


  • Class characteristics
    • Shed everywhere
    • Shed all the time
    • Miscarriages of justice possible- hair misidentified, science is not exact
      • Evidence not consistent (human vs. animal hair, DNA extraction not possible)
      • Now only used as corroborating evidence

The entire study of forensic biology is identifying what we know and gathering evidence, then using proven techniques to establish and corroborate facts.

What do we need to know?

One method Dr. Warren touched on was using different indicators to identify blood. Something that I found very interesting was that these indicators (Luminol, Bluestar) glow because of the iron in blood, and false positives are possible if other iron-rich materials are present, so it is important to always corroborate this test with another, confirmatory test. So, we always need to know whether the presumptive test that was used is correct.

  • Presumptive
    • Luminol
    • Haemastix
      • Turns green with blood
        • False positives
          • Bleach rust
        • Interferes with DNA analysis
    • Bluestar
      • Okay with DNA
    • Kastle Meyer/ phenophalene
  • Confirmatory test
    • Only haemachromagen test
    • No false positives
    • Chemicals added to blood sample
    • Turns into crystals
    • Still don’t know what type of blood it is
      • Animal?
      • Human?
    • Precipitin test
    • Commercially available anti-sera
    • Old- blood type
    • DNA testing as of 1985
      • First brought into court
      • Lester, England

What is missing?

Something that was interesting that Dr. Warren talked about was the possibility of false positives with PCR because of the amplification of the DNA. I found it interesting because we don’t have a way to check whether it has been contaminated once run through the machine, and we can only take steps during the collection process to try and minimize this risk.

What questions should we ask?

  • When was the crime committed?
  • How did the crime occur?
  • What happened (classification)?
  • Why (Motive)?
  • Who (DNA evidence, suspect)?
  • Where (secondary location)?

How might we get the information we need?

We can gain the information we need through a variety of presumptive tests, which we in turn corroborate with a confirmatory test. This is true for any biological fluid, including blood. The presumptive test is run first, then the sample is sent off to another lab where a confirmatory test is run.

Red Hat:

Dr. Warren talked about a specific case where the police officers had only used a presumptive test and their intuition to convict an innocent person. She warned us of the dangers of assuming without corroborating our evidence.

  • Might be blood
    • Dingo baby case
      • Australia
        • Family camping in Australia
        • Dingo running out tent with baby in mouth
          • Mother accused of murdering baby
            • Killed baby with nail scissors(?)
              • While everyone was out looking for baby
              • Got rid of body
                • Only used a presumptive test
                • Need to use a confirmatory test
              • Baby’s jacket found in Dingo’s lair
                • Disrupted life
                • Car glowed when sprayed with luminol
                  • because of Iron filings

Black Hat

The black hat is especially important because it can be used to turn a critical eye over any evidence, which is very important to ensure that the evidence is accurate and as presise as possible. One of the tests Dr. Warren talked about was hair analysis, and the limits of it. For example, DNA can only be extracted from hair if it still has the bulb at the base of the hair, because this is the living part. You also need anywhere from 80-100 pulled scalp hairs to precisely determine the person who the hair belonged to, so there are limits to using hairs to prove/disprove a suspect’s involvement. Also, before DNA was used, foresnic scientists used to examine the cuticle and medula, and this led to a couple of wrongful convictions, so it is always important to be critical when using hair as evidence.

    • Not consistent with donor
    • Contained too few hairs?
  • Negative
    • Consistent with donor
  • Positive
    • Comparison sample needed
      • Suspect and victim
        • Need some from victim
          • What if they are from the victim
    • Adequate sample required
      • 80-100 PULLED scalp hairs
      • 30-50 PULLED pubic hairs
      • From all over region
        • Temples vs. Back of head
        • Comparison sample
      • Collect from
        • Partners, victims
  • Hair Collection
  • Hair is considered class evidence
    • Except with tag
      • Loose, extraneous hairs are class evidence

Yellow Hat:

This hat was used to explain the value in using confirmatory tests in addition to presumptive tests. This goes along with the red hat, as value is found in having a correct conviction and ensuring innocent people don’t go to jail. Standardized protocol is used to ensure preservation of this hat.

Green Hat:

This hat was used when Dr. Warren talked about the career path to become a specialist, specifically a forensic biologist.

  • Civilian Scientists
    • B.Sc. (Hon.)
  • Technicians
    • Evidence Recovery Unit (a lab)
      • Evidence Recovery Unit

        • Search technologists
        • Locate and recover important evidence
        • Everyone starts here
        • Presumptive tests
          • Blood? Or other iron rich substance?
      • In lab
        • T-shirt (with blood on it)
          • Blood (possibly) sample cut out
            • Sent to specialist
  • PCR Analyst (3-5 years past evidence recovery unit)
    • Extract DNA
  • Specialist
    • Testify in court
    • Biology reporting office
      • Stats, probability
      • Likelihood of someone matching this sample
  • If no honors –  remain at the level of technician

Blue Hat: This hat was in use when Dr. Warren outlined Forensic Biology at the beginning of the lesson.

  • Biological fluids
    • Hair
    • Tissues
    • Blood, saliva, etc.
  • Human?
    • Can it be individualized?
      • Who?
  • In past- class evidence
    • Hair
    • Use DNA now
  • Present- now use DNA as prefered method of corroboration

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