Glad you found three of your birds. I have electric wires around my coops and pens, good heavy duty netting covering all of my pens and concrete under the gates all due to losses from predators in the past. I also have several game cameras. When I first put my cameras up I was surprised at the predators that roam here especially at night. A fox can take a bird and it's probably in its den so you won't find it. I had a fox dig under a gate years ago and kill several birds. I caught it in the act of dragging them out back under the gate. I chased it off but it kept coming back so I set traps out and used one of the birds bodies to catch it and eliminated it. It looked fluffy but after I eliminated it, it was mangy and stinky. If you have a wildlife rescue in your area, they may come and trap them or if you want to trap them they would probably come and take them. I had an owl that was a menace. I actually accidentally caught it and a wildlife rescue came and got it and said they had a release area so it shouldn't come back. That was another issue. Nothing has gotten past the electric wires and I love my cameras. Good luck...I'm so very sorry. That must have been terrible. If you only have one lock, lots of people have gone to having one at the top of the door and another at the bottom, as an extra safety feature. That way if they get the first latch open, they are unlikely to get the second one too. Electric wire is a godsend. Game cameras help and if the coop isn't super far from the house, you can get a baby monitor to hear if they are freaking out. That's what I plan to do with my ducks but any predator is going to have to brave multiple layers of serious security.