Chemical or isotopic labels are added to, e.g., a potentially lethal drug formulation, to generate a unique chemical fingerprint. Combinations of chemical additives are mixed with the drug to aid in their isolation and identification, especially when such drugs are used for illicit purposes. When stable isotopes are incorporated into lethal drugs, the labeling process conveys a very unique internal chemical signature and greatly aids in the identification of the parent drug in body fluids and tissues. When heath-care providers become aware that certain drugs can now be easily tracked and identified in a victim, individuals may be reluctant to utilize these agents for ill purposes.