Legal basis: Criminal Procedure Law of People's Republic of China (PRC).
Article 82 A public security organ may detain a flagrante delicto or a major suspect in any of the following circumstances: (1) a person who is preparing to commit a crime, commits a crime or is found immediately after committing a crime; (2) The victim or a witness on the spot identifies him as a criminal; (3) criminal evidence is found around him or at his residence; (four) attempted suicide, escape or escape after committing a crime; (5) It is possible to destroy or forge evidence or collude with others; (six) do not speak the real name and address, the identity is unknown; (7) Being seriously suspected of committing crimes on the run, committing crimes for many times or committing crimes in association.
Article 85 When a public security organ detains a person, it must produce a detention permit. After detention, the detained person shall be immediately sent to the detention center for custody, and shall not exceed twenty-four hours. Unless it is impossible to notify or the notification of suspected crimes endangering national security or terrorist activities may hinder the investigation, the family members of the detained person shall be notified within 24 hours after detention. After the circumstances that hinder the investigation disappear, the family members of the detained person shall be notified immediately.