In this case, there will be many reasons for letting people go. Under normal circumstances, intentional injury causing minor injuries or more can be punished, that is to say, causing minor injuries or more is enough for criminal punishment, and minor injuries are generally administrative punishment. Because there is an economic dispute between you, if your uncle is slightly injured, the public security organ may not handle the criminal case, so the other party can pay a certain deposit to get the person out first. To say the least, even if the case is filed as a criminal case, other family members can apply for bail pending trial. Why is it specially released? I suggest you ask the public security bureau.
In addition, it doesn't mean anything when people are released, and you can claim compensation from each other for just reasons.