I saw a child kill his little brother while his mom was in the next room

I was in the kitchen in the apartment I used to rent, which is basically like a room rental. There was a family that lived in one of the rooms who had two boys, about 8 and 10. I had seen them a few times when I used to see the mom do the laundry. They were quiet kids and they did not seem too noticeable in any way. One day I was in the kitchen making some food for the day. The older brother walked in and asked if he could use the refrigerator. I said yes, and he put something inside and left. I don't think he even closed the door, but I wasn't sure about it so I checked and the door was open. I shut the door. Later that day I remember seeing the mom crying uncontrollably in the living room down the hall from the kitchen. I asked her what was wrong, and she told me her younger son died the night before. She said she fell asleep and the little one crawled into bed with his big brother and the big brother smothered him to death. I was horrified. I didn't know what to say or do. I remember seeing the big brother the day before and thinking there was nothing wrong with him. After the little brother died I never saw the big brother again. I never figured out what happened to him. It's been years now and I still think about this from time to time. I'd love to know what happened to the big brother, but he's probably grown up by now.<br><br>Edit: Looking back, this may have been SIDS and the mom accidentally rolled onto her baby. I don't know. I wasn't there to see it.