1) The law firm and the client signed an entrustment agreement in duplicate, one for the client and one for the law firm to file;
2) The power of attorney signed by the client is in triplicate, one for the case-handling organ, one for the lawyer and one for the client;
3) A letter of introduction from the law firm, which shall be submitted by the lawyer to the case-handling organ.
legal ground
According to Article 34 of the Criminal Procedure Law, a criminal suspect has the right to entrust a defender from the day when he is interrogated for the first time by the investigation organ or takes compulsory measures. During the investigation, only lawyers can be entrusted as defenders. The defendant has the right to entrust a defender at any time.