Investigation, legally speaking, refers to a series of special investigation means and compulsory measures taken by the investigation organ in order to find out the case, collect criminal evidence, confirm and arrest the criminal suspect and investigate his criminal responsibility. Investigation is a kind of litigation activity with specific content and purpose requirements, which has great significance and influence on the subsequent prosecution and trial, and has become an important content and basic link in the criminal procedure.
In criminal proceedings, procuratorial organs, public security organs and other organs conduct special investigations and take relevant compulsory measures in order to find out the facts of crimes and arrest suspects. Generally, it starts from filing a case and ends when the case decides whether to transfer it to prosecution. The so-called "special investigation work" refers to interrogation, inquiry, inquest, inspection, search, seizure of material evidence or documentary evidence, identification, wanted and so on. Carry out according to law and complete the investigation task; The so-called "related compulsory measures" include "two kinds". First of all, many special investigations, such as interrogation, search, seizure and wanted, are compulsory in nature. Second, compulsory measures such as compulsory summons, bail pending trial, residential surveillance, detention and arrest are specially applied to criminal suspects.
The main task of investigation is to find out the facts of the case. Criminal proceedings can be divided into three procedural stages: investigation, prosecution and trial. Investigation activities are mainly carried out in the investigation stage, but in the prosecution and trial stage, if it is necessary to further ascertain the facts of the case, supplementary investigation can be carried out according to law.