why didn't jack crawford know hannibal was the workshop guy doctor in the past and why didn’t he look into it?
Because medical records are private (always private, but more private post-HIPAA than when the books were written). That's why he looked the other way when Miriam Lass broke rules the "guru" couldn't, because for her it was better to ask forgiveness than permission. For him, not so much. Jack is also a team supervisor, not a primary investigator. He has other people do the leg work.
In the book, Will makes this leap as a routine part of the investigation, and it's how he catches Hannibal.















