Legal basis: Criminal Procedure Law of People's Republic of China (PRC).
Article 3 The public security organs shall be responsible for the investigation, detention, execution of arrest and preliminary examination of criminal cases. The people's procuratorate shall be responsible for the prosecution, approval of arrest, investigation and prosecution of cases directly accepted by procuratorial organs. The people's court is responsible for the trial. Except as otherwise specified by law, no other organ, organization or individual has the right to exercise these powers.
Article 82 The public security organ may detain a flagrante delicto or a major suspect in any of the following circumstances:
(1) Being prepared to commit a crime, committing a crime or being discovered 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.