I am so sorry this has happened to you. I would be purely depressed if someone stole my chickens - it is bad enough when critters take them, but when Humans steal them, that is a whole other breed of lowdown dirty dog.
Three of my coops are down in the donkey pasture - close enough to the house that I'd hear the donkeys going off and the guineas perch in a tree above the coop - so I have double protection there. The guineas will go off at the sight of a moth that happens to flutter to close to them, they'd for sure go off on something big enough to cut a lock and take chickens.
The fourth coop is within full sight of the house, so I doubt anyone would try to get in when I was home - and I am usually home. Still, it is worrisome that folks would do something like that, and I know people are getting more desperate for food and money.
Just last week I had someone poaching deer on my land. I am not anti-hunting - I am anti - shooting guns off around my family and animals and my home. My step dad had been down in those woods just earlier in the day - thankfully they didn't shoot him.
Like you said, I don't know what else can be done to protect your property, short of hiring someone to stand guard 24/7 and that is simply not practical.
makes me wonder what the world is coming to - and where it will be in another year or two.
meri