I have already stated the evidence suggesting he did not lock the door. Notably, the lack of a pause or even side-by-side shoeprints in front of Meredith's room. Rather, his shoeprints showed a stride directly out the door, down the hall, and exiting the cottage.
There is reason to believe Rudy did not act alone. The evidence for this has not been properly refuted, thus it is again apparent that you are not here searching for the truth, but rather limiting yourself to that evidence that suits the scenario you wish to believe. There is a name for this fallacy:
Confirmation Bias
It would serve you well, Charlie, to drop this fallacy and approach the evidence with a critical, open mind.