I think that would have been figured out. However, I see another scenario:
She checks herself out (given that she called about leaving I find it reasonable to think she might have), goes to the bathroom and arrests in a stall but is not discovered for a while.
The family is looking for her, the hospital correctly notes that she had checked herself out. Eventually her body is found. She's not a patient since she checked herself out. Somehow it fell through the cracks about notifying her family, or perhaps she didn't have ID on her and the body was sent as a Jane Doe.
She checks herself out (given that she called about leaving I find it reasonable to think she might have), goes to the bathroom and arrests in a stall but is not discovered for a while.
The family is looking for her, the hospital correctly notes that she had checked herself out. Eventually her body is found. She's not a patient since she checked herself out. Somehow it fell through the cracks about notifying her family, or perhaps she didn't have ID on her and the body was sent as a Jane Doe.