A multi-factor biometrics authentication method including the steps of: acquiring a non-spectrometric biometric signature (e.g. fingerprint, iris pattern, etc.) of a biometric signature source (e.g. fingertip, iris, etc.) of a subject to be authenticated (e.g. person); acquiring spectral information (e.g. diffuse reflectance spectrum, reflectance spectrum, etc.) of the biometric signature source; using the non-spectrometric biometric signature to determine the unique identity of the biometric signature source; and using the spectral information to verify that the subject to be authenticated belongs to a predetermined class of objects (e.g. living persons). A biometrics system (e.g. fingerprint authentication device, iris pattern authentication device) is augmented with spectral biometrics capability in a practical manner without introducing much overhead to the base biometrics technology or inconvenience to users.