Legal basis: Article 140 of the Criminal Procedure Law of People's Republic of China (PRC). When a people's procuratorate examines a case and needs supplementary investigation, it may return it to the public security organ for supplementary investigation or conduct its own investigation. In the case of supplementary investigation, the supplementary investigation shall be completed within 1 month. Supplementary investigation is limited to 2 times. After the supplementary investigation is transferred to the people's procuratorate, the people's procuratorate recalculates the time limit for examination and prosecution. If 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.