In order to find the answer to this reasoning horror story,

"My brother suddenly went crazy and killed the whole family." It can be seen from this sentence that it is not my brother who stated this matter, but a third party, because the third party is still alive and not dead, which means that the "whole family" is other people besides my brother and myself! Then my brother died, leaving me alone. The sentence "Your brother only killed one person" shows that "the whole family" is just a description error, because there are three people in the family! My brother is very calm. My brother killed a man, which was his father and which was his mother, and then my brother was arrested, and he was scared!