You are facing potentially serious charges.
Do not talk to the police without an attorney present. Although the police may hint that your silence is incriminating, or that cooperation will result in everything "going away," that is not how our criminal justice system works. You can, and should, refuse to answer any questions without your attorney present. (You are entitled to an attorney during "custodial interrogations" and at "all critical stages" of trial, pursuant to the 5th and 6th Amendments, respectively).
Your interests are adverse to your son's. The attorney you hire cannot represent both of you. If you are served with a criminal summons, or are arrested, you should hire an attorney immediately. If you cannot afford one, apply for the services of the public defender.
Both you and your son need to be represented by separate counsel. Both you and you son need to refrain from any further conversations with the police without counsel present.
You clearly need to consult a lawyer. It is very difficult to give specific advice in this type of forum. I suggest that you gather whatever information/evidence you have that you did not commit the alleged offence. I also suggest that you NOT speak with the police. If they think you did it, and charge you, you talking to them won't help. Let a lawyer do the talking. If you get arrested and/or charged keep your mouth closed.
Also, you are not aiding or abbetting a criminal by not saying anything. If your child stole the passcard from you, and you didn't know anything about it until afterwrds, you didn't do anything wrong. You need to contact an attorney.
Please understand, without forming an attorney/client relationship this office is not providing legal advice. We are simply providing general information which should not be acted upon without careful consideration and the assistance of an experienced attorney.
An attorney can assist you with evaluating the states case, any defenses that you might have, and any plea offer that might be made, so that you can decide whether to plea bargain or go to trial. If you were to be found guilty, then an attorney can assist you with presenting mitigation, allocution, and a recommendation for a more lenient sentence. Consider seeking a confidential consultation with an experienced criminal defense attorney. Beware that online posts are not confidential. If somehow the prosecution were to find your post, then it might be used in evidence against you.
Information in the reply is provided as a public service. It is neither a comprehensive statement of the law nor legal advice, and no one should rely on it as such. If you have a legal problem or question, you should consult with an attorney, who can investigate the particular circumstances of your situation. Responding to a post does not constitute legal representation. I am not your lawyer, until we make an agreement and I receive my fee. Beware that posts and replies are not confidential. Anyone can read them.