Hi, Pontiac State Hospital was torn down a few years ago, but I think that the Oakland County Courthouse may have their records.You could contact them.
Oakland County Oakland County Clerk 1200 N. Telegraph Rd. Pontiac, MI 48053-1008 Telephone: (248) 858-0560
They should be able to tell you what records they may have.If Crystal died there, they should have a record of her death.You could also check with Lapeer County to double check for Crystal's death records.If there was no stone for her, the society wouldn't have had it to transcribe when they read the cemetery at the Lapeer Home.Their contact information is:
Lapeer County Lapeer County Clerk 255 Clay St., Courthouse Lapeer, MI 48446-2205 Telephone: (810) 667-0356