There’s a story written in the book A sun and its shield. It happened right before the holocaust, in Hungary. There was a girl who visited her cousins who had a child, a baby. The girl was staying at their house and during the day a babysitter came. One day the babysitter bundled up the baby and told the girl that they were going for a walk. They went on a walk and came to a dark building. They went inside. The girl had no idea what the building was, she was a little girl, but she sensed something wrong and she didn’t like the looks of it and asked the babysitter if they could go home. The babysitter didn’t want to but after pleading and begging the babysitter didn’t want to make a scene, so they went home. That night the girl told the parents, her cousins what had happened. They realized that the babysitter had gone to church and had probably done before with the baby who knows how many times. They told the girl if you see anything else out of the ordinary, then let us know.
This happened many years ago, but it technically could still happen today.
Coming from personal experience, I once had a non jewish babysitter who wasn’t very nice and for some reason, my mother’s necklace was missing after the first day she babysat. After that first day she was fired.