Seeing Red – Presumptive Tests for Blood

Felicity Carlysle

Felicity Carlysle

Felicity Carlysle is a 2nd year Forensic Science PhD student at the University of Strathclyde.

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7 Responses

  1. Tana Adkin says:

    Dear Felicity,
    I have a question about presumptive tests to distinguish animal from human blood. How reliable are these tests? If you could email me some advice or where to find out I’d be most grateful.
    Many thanks,
    Tana Adkin
    Charter Chambers

    • M.Barker says:

      Presumptive blood tests cannot determine the origin of the blood, it can only determine if the stain is most likely blood or not blood. If you get a positive result from a presumptive test and the stain appears to have the appearance of blood (i.e. red/brown) then there is another test called the ABA Hematrace test that can easily and rapidly determine whether or not the presumptive blood is of human origin. If this test is negative, then there are further immuno-diffusion tests that can identify the most-likely species of animal blood that this sample originates from.
      Hope that helps.

      • Rachael says:

        I have a question as i am trying to outline a plot for a book (fiction, thriller crime) My idea was for the perp to use pig blood in order to make it look someone had been murdered (no body) would they be able to tell at the scene that it animal blood? Or would it need more rigorous tests? Also, if it did, how long do these tests take?

        thank you!

  2. felicity says:

    You have my name
    and job

  3. christina says:

    I have a question: are there other reasons for a false positive other than some vegetables?

  4. Lee says:

    I have same type question as Christina on false positives. Specifically, would fecal matter produce a false positive on these tests? What would be the best test for distinguishing blood from fecal matter? (would also be curious to learn more on how florescein works) Thanks.

  5. la4'sha says:

    I have a question, why does the liquid only change into one color? and is there any other glow in the dark colors?

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