I work in politics, and my Board of Elections refuses to remove dead people from the voter rolls unless "a family member writes a letter" requesting removal.
I was the Chairman of the County Legislature, and they would not even accept me personally telling them someone is dead - verified by newspaper obit and our own County Health Department.
So that means - there are dead people all over the place still registered to vote. I keep my own list of dead enrolled voters because it is embarrassing when you go to doors either to campaign or get signatures and you ask for the dead person.