The present invention relates generally to non-invasive methods and apparatuses for determining analyte properties of a subject and identity characteristics of a subject. Embodiments of the present invention provide analyte property determination and identity determination or verification from the same spectroscopic information, making unauthorized use or misleading results less likely that in systems that include separate analyte and identity determinations. The invention can be used to prevent operation of automobiles or other equipment unless the operator has an acceptable alcohol concentration, and to limit operation of automobiles or other equipment to authorized individuals who are not intoxicated or drug-impaired.