Custody and Visitation Issues: One Parent Passed on Child's Custody

My question involves a child custody case from the State of: Maryland. This young woman has brain damage and has been declared incompetent. She resided with her biological mother and a stepfather. Her mother became ill and passed away today and the biological father who has never relinquished any parental rights, was with his daughter at the time when her mother passed. He went to the mother's home with his daughter to retrieve her things but the stepfather is now barring that and is threatening the father with jail if he attempts to return. He has no documentation with him as this what not what the stepfather and he had agreed to. What must he do to get his daughter? Is this not kidnapping?

Custody and Visitation Issues: One Parent Passed on Child's Custody