Legal basis:
Criminal Procedure Law of the People's Republic of China
Article 115 A public security organ shall investigate a criminal case that has been put on file, and collect and obtain evidence of the criminal suspect's guilt or innocence, whether the crime is minor or serious. An active criminal or a major suspect may be detained in advance according to law, and a criminal suspect who meets the conditions for arrest shall be arrested according to law.
Article 116 After investigation, a public security organ shall conduct a preliminary examination of a case with evidence to prove that there are criminal facts, and verify the evidence materials collected and collected.