Criminal detention is a compulsory method for public security organs and people's procuratorates to temporarily deprive criminals or major suspects of their personal freedom in case of legal emergency during investigation. Criminal detention must meet two conditions at the same time: first, the object of detention is a flagrante delicto or a major suspect. An active criminal refers to a person who is committing a crime, and a major suspect refers to a person who has evidence to prove that he is suspected of a major crime. Second, it has one of the legal emergencies.
Article 84 of the Criminal Procedure Law: The public security organ shall interrogate the detained person within 24 hours after detention. If it is found that it should not be detained, it must be released immediately and a release certificate will be issued.