legal analysis: necessary. But this is a notice. If the parties do not sign it, the legal effect of the notice will not be affected as long as the case-handling personnel indicate the relevant information. At present, there is no clear stipulation in our country's law on whether the public security organ should issue a written notice of filing a case to the informant. If the informant is the victim or interested party of the case, it will generally notify him.

legal basis: article 111 of the criminal procedure law of the people's Republic of China, reports, complaints and reports can be made in writing or orally. A staff member who accepts an oral report, complaint or tip-off shall make a written record, which shall be signed or sealed by the informant, complainant and informer after being read out correctly. The staff who accept the complaint or report shall explain to the accuser and informant the legal responsibility for the false accusation. However, as long as the facts are not fabricated and evidence is forged, even if the facts of the accusation and report are different, or even false accusations, they should be strictly distinguished from false accusations. Public security organs, people's procuratorates or people's courts shall ensure the safety of informants, complainants, informants and their close relatives. Informants, accusers and informants should keep secrets for them if they are unwilling to disclose their names and the acts of reporting, accusing and reporting.