My sister whom i have guardianship of, left home without my permission and I recently found out she is staying with her ex-husband who is also mentally ill. The police went to his house and he told them she was not there. Then I called the adult crisis center to issue a mental health warrant on her, but they said she needs to be a danger to herself. Since he is breaking the law, can't I have a warrant for his arrest issued on the grounds of harboring a run-away? I know she is an adult, but she is not her own person and she did not have my permission to leave home. I spoke to an elder law attorney who said she would try to get the mental health warrant agreed to, but if not I want this man arrested for breaking the law.
If you trust that lawyer, stay with her. A habeas might be another route to go. The law moves more slowly than you would like, especially on the weekend, but it will move forward.
If he is not preventing her from leaving, then he is probably not in violation of the law at this point.
This answer DOES NOT establish an attorney-client relationship. This answer is based on the limited information provided and is not intended to be conclusive advice. There are likely other factors that might influence or change the advice after a more lengthy consultation.