Legal Question in Family Law in New Mexico

Harder question than you might think.

You could conceivably be charged with "custodial interference" NMSA 30-4-4(B), a fourth degree felony - if the father could demonstrate that he is a person with a "right to custody." Considering his absence from the child's life he may not be able to do that, but a court would have to decide.

A better course in my opinion would be to file a paternity action to establish the paternity of the child and get a court order granting you exclusive custody (and maybe child support). This would lift a cloud over your and the child's heads that will follow you for 18 years and may pop up in unexpected ways down the road to complicate your life.

If you don't want to do that it would be prudent to at least notify the father you are leaving with the child, establish a way he can contact you if necessary (through a third party to avoid harassment), and see if he will give you a notarized letter acknowledging that he has agreed to having you take the child out of the state.

I know this sounds like a pain, but better to suffer some pain now while you are still here and can contact him, than to have the child's paternity become an issue when you're in the middle of making some big move in your or your child's life years from now. This would be a good time to get a lawyer.