Sign the evidence materials for confirmation. Assist in the investigation and sign some supplementary materials at the same time. If you need to supplement your previous confession, you should continue to supplement and sign it. Other evidence materials need to be signed and confirmed, and some doubts need to be assisted in the investigation. Assisting in investigation is a voluntary act taken by citizens to maintain public order and good customs, social harmony and people's livelihood stability, and to cooperate with the police or other departments to carry out investigations.