This happened when I was around 12 years old. My mom took my siblings and I to visit her mom in her home town in Mexico during our summer break. As soon as we got there we were told not to wander close to the neighbor's house; strange things seemed to be happening there.
Apparently, the 16 year that lived across the street was possessed. My grandmother actually used the phrase 'has the devil in her'. It started with the girl (don't remember her name) hearing somebody whisper, then she claimed she was able to hear footsteps that followed her everywhere. She stopped eating, sleeping and every morning would find scratches and bruises all over her body. The priest had been called and he had blessed the house several times but it didn't seem to stop. Her parents had to send their other children to stay with grandparents because they were too scared to stay in the house with her as she was beginning to have violent/manic episodes. Some people in town said that when they walked by that house they felt uneasy and some even claimed they saw shadows and heard strange noises.
My cousins were scared to walk by there and would rather go the opposite way and walk around the block just to get to a store that was two houses down from that house. By the way, this house was across the street from my grandma and two houses to the left (two houses left of the house that was right across the street). Hope that makes sense. I'm not going to lie, I was scared too but I also had this morbid curiosity, every time we had to leave my grandma's house I looked that way and stared, don't really know what I was hoping to see.
One morning, I woke to the grown-ups talking about what had happened across the street during the night. Apparently, a big stain appeared overnight in one of the walls. A stain that looked a lot like blood. They washed the stain with soap and water and painted over where the stain was. By that evening, the stain was there again. They went to get the priest and once again cleaned the stain and prayed while the priest blessed the house and threw holy water at the wall. By morning, the stain was back. The word around town spread and people had gathered and formed prayer groups. It seemed they were praying non-stop. One group of people would leave and others would show up. All carrying rosary beads.
My cousins, siblings and I were under strict orders not to get close to that house, my grandma thought we might also get possessed or something might follow us home. Of course us being kids, we decided we wanted to go and look at this blood stain on the wall. So off we went, hiding behind other people so our grandma and mothers wouldn't see us.
There was a lot of people and not everyone fit inside the house, or they were afraid to go in, there was a lot of people just outside the entrance. As we got closer, we heard a girl yelling as if in pain, we also heard growling but I'm not sure if the girl was also making these noises. Everyone there was praying the rosary in unison but you were able to hear the girl's voice crying and asking for help. Then she would start yelling, screaming and you would hear growling. At this point, my cousins, my brother and my sister had turned back in fear. My sister grabbed my arm and tried pulling me back but I had to see for myself who was making those noises. I pushed my way inside the house and what I saw next I will never forget.
I saw a girl tied with ropes to a bannister of the house. She looked to be almost just skin and bones, I don't know what I was expecting to see but it shocked me and I gasped. For a second there it almost seemed like she heard me and turned my way, I swear she was staring straight at me and smiled. I was frozen in my spot unable to move. Then I felt someone pull me back so hard I almost lost my balance. It was my grandmother that was dragging me out of there. I don't think I ever saw her that mad, she was fit to be tied. As was the norm, I got in a lot of trouble for disobeying only this time I was really sorry that I did. I was so scared and kept seeing the girl's face and grin in my head every time I closed my eyes. I thought for sure she was going to get loose and come for me.
Days after that we headed back home to the U.S. Last I heard the girl had gotten better. No one is sure if the priest coming over and blessing the house every day or the town folk praying non-stop is what helped her but they say that a witch (brujo) was also summoned. His belief was that this was not a demonic possession but a very strong case of witchcraft/black magic. Apparently, this was done to her out of jealousy. She was very pretty and caught the eye of the wrong man. After she got better she was sent away to live with relatives in the U.S.
I don't know exactly what was wrong with her and how she got better. All I am sure of is that I saw her with my own eyes, saw the condition she was in and heard the most god-awful noises come out of her such as I've never heard before. Many years have passed, but this is something that is very clear in my memory, I still remember that face and that smile and it still scares me to this day.