KittySlayer
Grandmaster
I would be talking to neighbors (and possibly the real estate agent?) to see if a Joe Owens did previously live in the house....
A great conversation to have with neighbors. You get to know who your neighbors are. By asking about Joe Owens you can relay (parts of) the story without sounding paranoid. Hopefully it will make your neighbors keep an eye out for unusual people too. They may share other unusual experiences they have noticed. More eyes on the situation can only help as a camera cannot call the police but a neighbor could.
...never leave the door open...as you found out it only takes a moment to be caught off guard so eliminate as many factors as possible...
A good reminder as spring is right around the corner. Don't be around the corner of the house working on the landscaping with the garage door open. Don't be around the corner of the house working while unarmed.