Dr. Spencer Reid:  The pattern in the branding mark has design characteristics similar to family crests from the late middle ages . I found this encyclopedia of heraldry and look .
Aaron Hotchner: It 's the seal of William Stoughton , a magistrate .
Dr. Spencer Reid: Check when and where he 's a magistrate .
David Rossi: Salem , Massachusetts , _ 1692 _ .
Dr. Spencer Reid: Stoughton was the lead prosecutor in the Salem witch trials .
Aaron Hotchner: So this UnSub believes he 's hunting witches .