Hello, generally speaking, lawyers in criminal cases will ask the close relatives of criminal suspects to sign a power of attorney. Criminal suspects who are not released on bail pending trial or under residential surveillance are detained in detention centers, and it is more convenient to entrust them by close relatives. For details, please refer to the Criminal Procedure Law of the People's Republic of China: Article 33 During the period of detention, a criminal suspect or defendant may also be entrusted by his guardian or near relative.
Article 4 The victims of public prosecution cases, their legal representatives and close relatives, and the parties involved in incidental civil actions and their legal representatives shall have the right to entrust agents ad litem from the date when the case is transferred for examination and prosecution. The private prosecutor and his agent ad litem in a case of private prosecution, the parties involved in an incidental civil action and his agent ad litem have the right to entrust an agent ad litem at any time.