Zyklon B came to El Paso in the 1920s. In 1929, for example, a U.S. Public Health Service officer, J.R. Hurley, ordered $25 worth of the material–hydrocyanic acid in pellet form–as a fumigating agent for use at the El Paso delousing station, where Mexicans crossed the border from Juárez. Zyklon, developed by DEGESCH (the German Vermin-combating Corporation) was made in varying strengths, with Zyklon C, D and E representing gradations in potency and price.