Outside of hiring a lawyer, here's what I would do first:
1. If you can prove what you just said by eye-witnesses, write up an affidavit and have them signed by witnesses and notarized.
2. Find out who Todd's supervisor is (get the name). Write the officer a letter, acknowledging your phone conversation and then reiterate the facts and attach the affidavits. If you get the info on the other person, include that. Be sure to cc his supervisor - it will make him think about doing things correctly. It will also show him that you've been doing some investigation on your own.
3. Find out what your rights are for mistaken identidy.... I believe they have the burden of proof.