I was at Mom's today.
I was mystified when Honey, the little dog, was able to pass through the locked exterior door like a ghost.
It turns out that there were two things wrong with the door. The latch bolt was stuck in the carrier and did not want to engage the striker plate.
Somebody in the past week noticed that fact and fixed it...sort of. They lubricated it and reinstalled it but they installed it backwards so it pushed open from the outside.
Oh, and the latch bolt still stuck in the carrier.
Mrs ERJ sent me forth to Yee Olde Big Boxe Store.
I admit to admiring Schlage locks. $44 bought a combination exterior door handle and dead-bolt combination. Another $33 for an additional 11 keys for all of the people who care for mom.
I made doubly sure to ensure that the latch bolt was not installed backwards.