Legal analysis: The reason why the police want to leave identity information is to determine the identity of the informant and the authenticity of the report, and false accusation needs to bear legal responsibility. Many times the informant plays an important role in the process of case detection, and sometimes it will provide important clues for case investigation, so it is necessary to leave all kinds of information. However, the public security organ, the people's procuratorate or the people's court shall keep secrets for the parties concerned if the informant, accuser or informant is unwilling to disclose his name and the act of reporting, accusing or reporting.

Legal basis: Article 111th of the Criminal Procedure Law of People's Republic of China (PRC). Reports, complaints and reports can be made in writing or orally. The staff who accept the oral report, complaint or report shall make a written record, which shall be signed or sealed by the informant, complainant and informant after being correctly read out. The staff who accept the complaint and report shall explain the legal responsibility of false accusation and frame-up to the complainant and informant. However, as long as it is not fabricating facts and evidence, even if the facts of the accusation and report are different, or even false accusation, it should be strictly distinguished from false accusation. Public security organs, people's procuratorates or people's courts shall ensure the safety of informants, complainants, informants and their close relatives. Informants, complainants and informants who are unwilling to disclose their names and report, accuse and report their acts shall keep them confidential.