It would have been mighty cold for Mary, lying there naked or in a thin chemise in that freezing room with holes in the window panes had she been alone and not stripped for business purposes.
There is no "certainty" at all that Kelly ever wedged a chair in front of her door when sleeping alone, and in her inebriated state on the morning of her murder, it is more than likely that she overlooked such precautions. It is possible that Blotchy left the room after Kelly fell into a sozzled slumber, leaving the door "on the latch", and enabling her murderer to creep in at some point thereafter without creating a disturbance. Even if the killer found a locked door, he may have remedied the situation by reaching through the broken window and unlocking it from the inside, as both Kelly and Barnett had been accustomed to doing.
but I don't believe Jack was a burglar
If we’re prepared to make allowances for change when it came to the type of venue targeted by the killer (as opposed to assuming that a different killer was responsible), it is only fair and logical to make similar allowances for the type of pre-crime approach he adopted. Ted Bundy altered his approach to suit different circumstances. When out and about, he adopted a false guise to inveigle them into this company, but when it came to the indoor Tallahassee murders he simply broke into the girls' rooms after monitoring the building from a vantage point, just as Robert Napper and Dannis Rader did.
Regards,
Ben
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