"すべての殺人者はおそらく誰かの古い友人です"

Simplified Meaning:

Sometimes people who do very bad things, like committing murder, were once just normal friends to someone else. Think about someone you know well – they could be a relative, a neighbor, or a school friend. Imagine if you learned that this person did something terrible; it would be shocking because you remember them from daily life and good times. For example, there are stories where people from small towns grow up, and one of them ends up committing a serious crime. Their community and friends would probably be surprised because they knew the person differently, maybe as someone who played sports with them or helped them out. This shows that evil actions can come from unexpected places and reminds us that everyone has a history and relationships. It makes us think about the complexity of human nature and the fact that people can change in ways we might never predict. Understanding this can make us more aware of the hidden sides of others and the potential impact of their choices.