Legal Question in Family Law in New Mexico

That's a tough question. I don't know of statutory criteria. I'm giving you a synopsis of a case involving unfitness.

Express findings supported by substantial evidence necessary where natural parent denied custody. � As against a third person, a natural parent would be entitled as a matter of law to custody of the minor child unless there has been established on the parent's part neglect, abandonment, incapacity, moral delinquency, instability of character or inability to furnish the child with needed care, or unless it has been established that such custody otherwise would not be in the best welfare and interest of the child, and the trial court must make express findings supported by substantial evidence if the natural parent is to be denied custody, not only that the parent is unfit, but that the third person seeking to obtain or retain custody is fit and the welfare and best interests of the child would best be served by giving custody to that third person. In a custody dispute between a natural mother and the children's grandmother where there were no express findings concerning the fitness of the parties and the evidence adduced at trial was meager, the case was reversed and remanded for a new proceeding to be held consistently with the proper presumption and burden of proof. Shorty v. Scott, 87 N.M. 490, 535 P.2d 1341 (1975).

Hope that helps. I think it's tough to do but CYFD does it all the time.