Don't let anyone on your yard.
I would venture to guess 85% of dog theft is from those who know their target.
They have seen your yard, scoped it out, watched you and your schedule and walked right in and taken your dogs.

I have 13 dogs stolen from me (all within a two year time frame - BAD LOCATION). I was very fortunate to get 11 of the 13 back. A lot of BS came from it. Babesia, good young dogs ruined, etc. But, a lot of sorry POS went to jail as well. Was in good with the local Sheriff deputy so retribution got jacked on up a little higher than it was actually.

If you limit who is allowed on your yard, you limit opportunity for theft and you narrow down the possibilities of WHO TOOK THE DOG, if it ever shows up missing again.

Since then, I have made it a point to never live any place my dogs are visible to anyone. You cannot see a single dog on my place now, even when you are on my place.

I do like Jack. They are welcome to come down and visit, IF I KNOW AND TRUST YOU. If not, you come down, I'll meet you at the local convenient store.