Electrophoretic techniques were used to prove illegal hunting of a protected species as small amounts of dried blood stains could be clearly identified as of otter origin. Species differentiation between the otter (Lutra lutra) and pheasant (Phasianus colchicus) was based mainly on small differences in electrophoretic mobilities of the respective albumins and hemoglobins in one-dimensional separations. Additional differences in minor proteins of the two species were revealed by two-dimensional electrophoresis. Electrophoresis thus also proved to be a valuable tool for forensic purposes.