I would like to note that Luigi has not been found guilty of anything and that both him deserving the presumption of innocence as well as the shooting being justified can be true at the same time.
The police are trying to convince the public that he did it so they can make a show out of punishing him to deter future acts against the rich, we shouldn’t do part of their job for them.
Luigi Mangione has not been found guilty of any crime. As of the time when writing this, he is an innocent man suspected of committing a crime. Until proven otherwise, he is not the person who shot the CEO.