I don't think it had to be a stranger at all.I want to see those men who were stayingat the Whites' for the holiday thoroughly investigated. I want to see Joe Barnhill's son thoroughly investigated. I want to see Santa's son checked out. I want to see LHP's son-in-law totally checked out. Anyone from the college who had been to the house with JAR for any reason - - I want to see them considered.
I am NOT stuck on the killer being a stranger at all.
My personal theory is that the killer is someone who didn't know how to spell JonBenét's name - - otherwise it would have been in the ransom note. And I think the person was far enough removed that he didn't concern himself about the Ramseys being able to ID his handwriting.