In the early twentieth century, the average American medicine cabinet was a would-be poisoner's treasure chest. There was radioactive radium in health tonics, thallium in depilatory creams, and morphine in teething medicine and potassium cyanide in cleaning supplies. While the tools of the murderer's trade multiplied as the pace of industrial innovation increased, the scientific knowledge (and the political will) to detect and prevent the crimes lagged behind.