So a Robber comes in a shoots the friend. His best friend was in the movie for 3 minutes. We have to care about our lead. This is where many new writers get into trouble. They try to let the story carry the script.
Story is important, but it has to work in conjunction with the characters.
If he escaped and tried to find the person responsible. What I am doing here is what I do when I get an idea. I explore every avenue to see where it takes me. I know that if he was falsely accused of murder, then we are rooting for him to prevail. I'm just trying to show you how each thought can branch off into another.