I can't say if it is the same everywhere, but I can tell you how my home was run. So, the state hospital wouldn't have anything to do with his oversight. People are usually either recipients of services from community based services (group/ community homes, independent living, respite care) or they live in the state hospital. Only the most severe cases still live and get services from the hospital. Other than maybe a mental health checkup.
The state is responsible, though. Just not the state hospital. Most states have regional offices. The regional office keeps packets of recipients wanting placement. The providers review the pcakes and interview those they feel they can serve, when they have a vacancy. So, the state knows who the person is, has referred them to the agency and participates in the planning process. Any big issues with the client, you have to call the regional rep and let them know. I can't say the regional office visited every client quarterly, except those who were under certain circumstances, but I can't remember.
In addition to the state offices on the regional level, the actual state auditors came in once a year. They audited all books, medication, programs, as well as interviewed each client alone, without staff present. They stay for about 3 days and it is exhausting. They watch everyyhing you do. What you teach, how you teach, what you cook, how you cook, they take the temperature of the food and time how long it is on the table before consumed. It. Is. Intense!! And all the while, they run you ragged asking for tons of pieces of paper and documentation.
In addition to Aaallll of that, they have appointments that are required on scheduled basis. Dental (usually every 3 or 6 months), nutrition every 3 months, nursing minimum every 3 months, usually monthly, psychological every year or up to 3, psychiatrist if needed, optometrist, hearing, general physician usually every 3 or 6 months.... and the weirdest to me, they go to a day program, work or school mostly 5 days a week. So, where was he supposed to be all week? No none there knew he wasn't showing up?
Anyway, point being, there are state agencies and oversight. They are not there daily. The hospital likely didn't do anything wrong. But many many many people did. And they all need to be held accountable. ESPECIALLY since he was interdicted. That blows my.mind. The Guardian should be in some seriously hot water. Someone got his rights removed and placed with someone else. That someone else let.him die without knowing for months. Not ok on any level. He was basically handed to someone to care for like a child. He was deemed unfit to make decisions for himself. And he was still lost in the crowd. That blows my mind. If yall only knew how odd it is to get rights removed and how involved legal guardians are in everything you do, since there aren't many of them.