Photo Radar. What if it wasn't you?

[Wrongnumber]

What is the name of your state (only U.S. law)? Arizona

My husband received a ticket in the mail because my car is registered under his name,the person driving was me. My husband sent a copy of his DL with the appropriate portion of the ticket. Yesterday (a few weeks after mailing the ticket in) my husband got a call telling him that they were going to suspend his DL because they never received anything from him in the mail (yeah right!), unless he showed up in court to prove that it wasn't him in the photo. When he asked if that was all he had to do they told him that he has to tell them who it was and if he lies in court he can get in big trouble. They also said that even without his cooporation they will find out who it was and then that person will not only get the ticket but be slapped with late fines.
Part of me thinks that they were trying to scare him because I'm sure that in most cases where the person in the photo isn't the person being ticketed it is usually the spouse. So by telling him that the real driver will have to pay even more they might be scaring him into fessing up.
Does he have to tell them who it is or can he refuse without lying or getting in trouble?

 

[The Occultist]

He is required to respond to say "See? Not me!" but he is NOT required to tell them who it is (unless he is somehow subpoenaed to the stand and is then asked if he knows who was driving, but I don't see that happening).