Paul Uhlenhuth

Paul Uhlenhuth was a German bacteriologist and immunologist. He was a Professor at the University of Strasbourg, the University of Marburg, and the University of Freiburg. After he retired, he ended up leading his own research institute in Freiburg. It was known as the State Research Laboratory. In 1901 he developed the precipitin test, also known as the Uhlenhuth test. That test distinguishes the difference between animal blood and human blood. His discovery had a major impact in the forensics and criminal justice fields.

The German scientist found that if he injected protein from a chicken egg into a rabbit, and then mixed serum from the rabbit with egg white, the egg proteins separated from the liquid to form a cloudy substance known as precipitin. This means it forms an antibody. When testing for human blood, either a sample of the suspect blood is put into a test tube over the rabbit serum or it's used in the "gel diffusion" test, where it's placed in gel on a glass slide next to a sample of the reagent (anti-human serum). Then it passes an electric current through the glass, where protein molecules filter into the gelatin and toward each other. If a line forms where they meet it is called a precipitin line which means the sample is indeed human blood.

Due to the creation of the precipitin test, a serial killer named Ludwig Tessnow was finally captured. Tessnow was first accused of murdering and dismembering two young girls whose bodies were later on found in the woods. When questioned, Tessnow did have red stains on his clothing