The glass to the back door was broken to the outside. There have been reports of a 3rd man there. I wonder how far fetched a scenario it would be that they all three came home together and some sort of dispute arose during sex play. Then Paul retreats to a bathroom and pushes the button on his life alert activating a police response. The 3rd person (maybe already a felon) could have easily run for the back door and been unable to unlock the glass outer door.
The police in San Francisco wouldn't have found this to be anything unusual at all.
