A joint crime is a joint intentional crime committed by two or more persons. In this case, the three defendants had the intention to commit a joint crime and also committed a joint crime, which belongs to a joint crime.

Second, I think the three defendants are suspected of intentional injury and death.

The three defendants are joint criminals. Although the victim's death was caused by a sharp instrument injuring his chest, resulting in a large amount of blood loss, that is, this death was caused by Zhang's behavior, his beating behavior, and Zhang's beating behavior suppressed the victim's resistance. Zhang's behavior helps and promotes death, and he has an unshirkable responsibility for the result of death.