This pen-based, identity verification uses biometric technology. For use in commercial transactions at a point-of-sate terminal, a customer registers advising the system of a customer account that is to be used for payment. The customer also submits a digital signature for reference purposes--a fingerprint. The customer is then issued a transponder that links the customer to the customer account and to the reference digital signature. When the customer is at the point-of-sale terminal for making payment, an interrogator disposed at the point-of-sale terminal transmits a radio signal requesting identity verification. The transponder submits data to the interrogator. Thereafter, when the customer uses a stylus to submit written data (a signature), a sensor in the stylus makes incidental capture of biometric data that enables the interrogator to confirm customer identity. Similarly, at a security checkpoint in an office building, the system is utilized when a written log is used to track access and egress to the building. Again, a transponder is issued to a party having authorized access after the party has registered and submitted a digital signature for reference purposes.