Emergency Guardianship

The place to start is in Arizona.  See if there are any court orders regarding the child.  Was your sister married? Where is the father of the child?  Has the child been taken into foster care?  You should contact the child welfare agency in the city or county where your sister and her daughter lived in order to let them know you are interested in taking care of the child. You may want to contact the bar association for the county to request a referral to an attorney who handles custody matters.  Normally if the father was around, he is entitled to raise his daughter.  You would need to serve him with the petition to establish custody if you start a suit to do so. You also need to check to see if your sister left a will or had created any kind of trust for her daughter. You will likely need to travel to Arizona to take care of this case, but the courts may also be willing to work with you via video conference due to the Covid-19 outbreak.