Is it clear how close they have to be to an ex-President at all times? Is the law written that they need to be in visual contact at all times? I have no idea.
I hadn't thought of it that way. He's definitely entitled to protection while in prison. I don't see any statute or regulation that sets a distance. They have to protect dude though.
It's called 'protective custody.' Child molesters, known stool pigeons, and ex-cops are kept in a separate area. Cells are locked 23 hours a day with one hour of exercise alone in a segregated yard.
There's no statute and the secret service doesn't comment on protection procedures. It'd be kind of silly if you could plan an assassination by just reading a law.
I imagine it's a case of the Secret Service coordinating with the State on how to handle Trump. No matter what he did, he's a former president, and is entitled to the protection of the Secret Service.