Well that is not good.
You could try a feeder in a clear critter carrier placed on the floor. I would use a live one so it will make noise. Then you have to hope the your snake is in range and hungry. If it is listen for the snake trying to get the mouse.
You can also sprinkle flour on the floor so you can see if it comes out and maybe get a direction of travel.
I hope it doesn't bite your neighbors baby.