@mavica a "spook" is a colloquial term for an FBI agent or similar if I recall.
My other goto name for Gastly is "Hopkirk"
As in "Randall And Hopkirk(Deceased)", a like, 60s or 70s TV series about a private detective who is helped out by the ghost of his murdered partner.
@mavica fuck cops tbqh though, hence not wanting to call this one that. She needs a better name