A tainted witness refers to a person who cooperates with the state procuratorial organ as a prosecution witness to testify against other criminals in order to reduce or exempt himself from criminal responsibility. The difference between a tainted witness and a general witness is that he is a participant in criminal activities, has a criminal stain, is not innocent, and his behavior already has the elements of a crime in criminal law.
The tainted witness has the following characteristics: (1) The tainted witness is the first person to know the case; (two) the crime is in line with the provisions of the criminal law, and it is a real crime that has not yet been sentenced to punishment; (3) testifying against others as a prosecution witness on the basis that the state procuratorial organ promises to reduce or exempt its criminal responsibility. That is, the person testifies for the national public prosecution agency in exchange for being exempted from criminal prosecution or being given a lighter or mitigated charge.
Article 68 of the Criminal Law stipulates that criminals who have made meritorious deeds such as exposing other people's criminal acts and verifying them, or providing important clues to solve other cases, may be given a lighter or mitigated punishment; Those who have made significant meritorious service may be mitigated or exempted from punishment.