The doors were auto close doors like you see in newer and good quality motels. The close by themselves, latch and once latched, they are locked. On of his neighbors has posted a youtube video of how they work.A good reason for locking your door.
Evidently, his closed but didn't always latch and lock..most of the time did lock but not always. I reckon he assumed it was locked.
This was one of the damning self testimonies she gave.
I do give her credit for being honest with her answers..........