This occurred to my father when he lived in California, about five years ago.
My dad was visiting some friends in an old farmhouse that they had just moved into. They asked him if he could watch over their newborn daughter for when they were going to bachelor and bachelorette parties. They told him that if he saw anything strange, they should just call him because there was a weird story that accompanied the house.
Apparently, the former owners had put in a pool for their eight year old daughter to learn how to swim in. Unfortunately, they had forgotten to take into account her sleepwalking. One night she went out sleepwalking and fell into the pool and drowned. Her parents found her the next morning. When her parents moved out, the only thing they left behind was a trunk filled with all her dress up things.
That trunk was in the baby's nursery, and my dad went looking in it to try and find something for the baby to play with. He found a little scribble drawing, but didn't think much of it and put it on top of the changing table.
He went into the living room to watch TV, so he took the baby monitor with him. About ten minutes later, the baby was making choking noises so he went to go check on her. He saw a grayish figure standing over the baby, with what looked like two arms reaching out and choking it. The room felt like it was below zero. When he walked near the baby, the figure disappeared. He called the parents and they promptly returned. My dad went home.
When he talked to them again, they told him they had gotten rid of the trunk and nothing had happened again.