Legal analysis: There are two procedural situations in supplementary investigation: 1. Supplementary investigation in the review and prosecution stage: 1. There are two ways of supplementary investigation in this stage. That is, if a case reviewed and prosecuted by the People's Procuratorate is completed by the public security agency and supplementary investigation is required, it can decide to return the case to the public security agency for supplementary investigation, or it can investigate on its own, and if necessary, can request the public security agency for assistance. However, if a case that has been completed by the People's Procuratorate on its own requires supplementary investigation, it cannot be returned to the public security organ for supplementary investigation. The method to be adopted shall be decided by the People’s Procuratorate. 2. For cases returned to the public security organs for supplementary investigation, the supplementary investigation shall be completed within one month; the time limit for review and prosecution by the People's Procuratorate shall be recalculated from the date when the case is transferred for prosecution after the supplementary investigation is completed. If the People's Procuratorate decides to conduct an investigation on its own during the review and prosecution process, it shall complete the investigation within the time limit for review and prosecution. 3. The number of supplementary investigations shall not exceed two. This refers to both cases that have been returned to the public security organs for supplementary investigation and cases that the People’s Procuratorate has decided to investigate on its own. 4. If after supplementary investigation of a case, the People's Procuratorate still believes that the evidence is insufficient and does not meet the conditions for prosecution, it may make a decision not to prosecute.

Legal basis: Article 199 of the "Civil Procedure Law of the People's Republic of China" If the parties believe that there is an error in a judgment or ruling that has taken legal effect, they may submit it to the people's court at the next higher level. The court may apply for a retrial; in cases where one party has a large number of persons or both parties are citizens, an application may be made to the original People's Court for a retrial. If a party applies for retrial, the execution of the judgment or ruling will not be suspended.