legal ground
Article 92 of the Criminal Procedure Law stipulates that the time limit for summons and detention shall not exceed 12 hours; If the case is particularly serious and complicated and detention or arrest measures are needed, the time limit for summoning or compulsory summoning shall not exceed 24 hours. Article 124 of the Criminal Procedure Law, investigators may question witnesses on the spot, or they may go to the unit, domicile or the place where the witness is to be appointed. 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.