I went to Anna's parents' house. They were able to fill out the story a little more and seemed to hope that I might be able to help them find Anna. I told them I was a private detective, and that the FBI (Dean and Sam, wouldn't you know) were also working on the case. They expressed surprise that the FBI would be interested in Anna, but seemed to believe me.
Anna is the "miracle" daughter of Richard and Amy Milton, who were an infertile couple until they had Anna. Apparently, when she was little, she claimed that Mr. Milton was not her real father, and that her real father was angry and wanted to kill her. Scared, the Miltons took Anna to a child psychiatrist, who convinced her that she was really a human and the Miltons' daughter, after which Anna seemed better. She was fine until about two months ago, when she came down with "schizophrenia" and thought that she could hear angels and that the Apocalypse was imminent.
The thing is, Anna's details sounded pretty accurate for a crazy person. She described the exact situation with the seals, and even had some interesting drawings. Putting two and two together, I decided Anna probably really could hear angels. I wondered if she was a cross, like me. If so, who was her father, and why would he want to kill her?
I'm headed back home for the moment. It will take the Winchesters at least two more days to get there, and I don't want to spoil their fun. Anyway, I want to see if my dad knows anything.