A college student in Nanjing was stabbed to death by his roommate because he didn't bring his key.

The first question: If the deceased took the initiative to provoke, there is a certain fault, which can be considered when sentencing;

The second question: If the deceased's behavior threatens the defendant's life and makes him pick up scissors and stab the deceased, causing other deaths, he should establish self-defense without any responsibility (this is excessive defense in criminal law), but this is difficult to judge. Generally, it will be considered as excessive defense and treated as intentional injury, but the punishment should be mitigated or exempted!