While it doesn't apply to my environment, I was made aware of this trick a few years ago. If you park in your attached garage with an electric door opener. A thief will prop a 12" piece of 2X4 against the door on either side. When you open it to pull out, the 2X4 falls flat. Then when you close the door, it senses the obstruction and re-opens.
If you drive off and don't wait to actually see the door stay closed for good, the thief enters, removes the 2X4 and gains access to the house after closing the door for privacy. They can leave the same way, and not leave any trace of how they actually gained entrance.
