Here are the circumstances:
A friend has a child with a woman he has never married. They are now separated and have been for 2 years. He takes his child every other weekend and her sister, an 8 year old, who is not his biological daughter, but the only Dad she has ever known. He adores her, but has no legal rights or even permission slips when she is with him. They have never had the conversation with her about his legal status as her father. When the mother travels for business or pleasure she requests that my friend care for their mutual daughter. He does so. He was asked, by email, if she could also watch both children this upcoming week. He declined for several reasons caring for the 8 year old but agreed to take the 4 year old as he is legally her father. He went to drop off the 8 year old on Sunday and the Mother had left on her trip. She will not return his calls, although he has confirmed with a third party that she is well and simply on travel. She left No clothes for the child, school books, note authorizing him to have guardianship while she is gone, nothing. He asked advice of her school this morning and was advised that his choices are do nothing or call police. He is fearful she would be placed into foster care immediately and he would not see her again, but does not want to let this go as he fears this could continue and/or be a small incident that is swept under the rug only to have a larger more painful incident arise in the future.

Questions:
What are his options? Nothing or Police? Please advise. Thanks much!

If he does call the school (and thus the police) social services will get involved, with the possibility of the 8 year old being placed in foster care.

The woman, who left on a trip and didn't leave clothes etc. is clearly negligent. Who will take the 8 year old if she is found to be an unfit mother? The man needs to stand up for himself, but, the 8 year old is innocent. What can he do? He needs advise from a professional. A social worker would be a good starting place.

Yes, the actual term will depend on the state law. It is worst than abandoment, since that normally in a legal sense is a parent who just does not do court ordered visits and the such over so many months or years.

But it may be the term used in some states, But yes this is a serouis issue and if reported most likely the child would go at least temp into custody of the family and children's service. There is often emergany care for short term while it is being investigated.

But if not, it is possible this will happen again and again.