Teichmann, Ludwig Karl

1823–1895
POLISH
ANATOMIST

Ludwig Karl Teichmann was a Polish anatomist and physician who made an enduring contribution to forensic science with his discovery of the Teichmann test for hemoglobin . Also called the Teichmann crystal, this is a test that is used on dried stains to determine whether or not blood is present. Dr. Teichmann made his forensic discovery in 1853. His microcrystalline test remains in use today as a means of identifying whether or not dried stains at a crime scene, on clothing or other fabric, or elsewhere at the site of a forensic investigation contain (human) blood.

Teichmann attended medical school in Gottingen, Germany. After completion of his studies, he remained at the university as an anatomy professor. In 1853, Teichmann published a scientific paper in which he described the crystallization of several organic compounds contained in human blood. Within his research paper, he explained a process by which microscopic crystals of hemin could be prepared. Hemin is a substance made up of reddish brown, microscopic, prismatic crystals; it is formed from dried blood by the action of common salt and strong acetic acid (the substance in vinegar that gives it a distinctive odor and pungent taste).

Blood begins to dry after 3–5 minutes of exposure to air, and drips or spatters (blood that is not in large quantities, like pooled blood) typically form crusts quite quickly. Dried blood can readily be confused with other substances, both organic and inorganic, at a crime scene. That is why, when a black, brown, brownish-black, or very dark red substance is found at a crime scene, it is necessary to determine whether or not it is actually blood. The Teichmann test is a presumptive test for blood; it is used strictly to screen for the presence or absence of blood. A positive result from a crystalline test is an indication to go ahead and use other tests to confirm.

see also Blood spatter; Bloodstain evidence; Cast-off blood; Crime scene investigation; Criminalistics.