1. A system comprising: (a) a receiver circuit configured to receive (i) a first reference image that includes a representation of a distinctive landmark subsurface feature of a body part of a known patient, the first reference image acquired by a body-insertable device deployed in the body part of the known patient, and (ii) a second reference image that includes a representation of a contemporaneously acquired landmark subsurface feature of a body part of a person presenting, the second reference image acquired by another body-insertable device deployed in the body part of the person presenting, the body part of the known patient and the body part of the person presenting being the same kind of body part; (b) a feature matching circuit configured to determine a substantial correspondence between (x) the distinctive landmark subsurface feature of the body part of the known patient and (y) the contemporaneously-acquired landmark subsurface feature of the body part of the person presenting; (c) a data circuit configured to generate informational data indicative of a verification of the person presenting with respect to the known patient, the verification at least partially based on the determined substantial correspondence between the distinctive landmark subsurface feature and the contemporaneously-acquired landmark subsurface feature; and (d) a communication circuit configured to output the informational data.