Now you can apply for criminal incidental civil action against the other party's injurer first. For the traffic police force, an administrative lawsuit is filed on the grounds of administrative inaction, so that its superiors can pay attention to this matter. You can also apply to the procuratorate for public prosecution.
The injured party may file a civil action incidental to criminal proceedings and investigate the responsibility of the party who caused the accident. Of course, you can also appeal to the procuratorate and ask for public prosecution.
It's been three years, so we should act quickly, especially civil compensation.