Legal basis: Article 124 of the Criminal Procedure Law of People's Republic of China (PRC), investigators may question witnesses on the spot or at the unit, residence or place proposed by the witness. When necessary, the witness may be notified to testify in a people's procuratorate or a public security organ. When questioning witnesses on the spot, they should show their work certificates, and when questioning witnesses at their units, residences or places proposed by witnesses, they should show their certificates from people's procuratorates or public security organs. The questioning of witnesses should be conducted separately.