The criminal case has been handed over to the city procuratorate, and the police have solved the case, but the victim's family did not understand the cause of the incident. What else can they do?

According to relevant laws and regulations, even criminal cases are not finalized before the court makes a final judgment. According to China's criminal procedure, although the police have solved the case at the first level and handed over the materials to the procuratorate as a prosecutor, they have no right or obligation to inform the families of the victims.

Judging from your description, all you can do is wait for the trial. If you want to attract public attention and attention, then you have a lot of things to do.

As the victim's family, although you have no right to know the whole case from the police, you can know your brother's situation from the police according to the citizen's right to know given by our constitution. Because the ins and outs of your brother's murder case and the relationship with the relevant legal subjects have not been clearly described, the possible punishment you mentioned in the judge's trial cannot be inferred according to the jurisprudence. But you can find a lawyer to defend your brother's rights according to the actual situation of this case.