The testimonies of participants in a criminal trial, obtained during interrogations, confrontations, and other investigative actions, form the foundation of the evidence base. However, the reliability of these testimonies depends not only on the integrity of the person being questioned, but also on the peculiarities of human memory, which is prone to unconscious distortions. The key mechanisms of these distortions are repression and substitution, psychological defenses that can lead to investigative errors. The purpose of this study is to investigate how the psychological mechanisms of information substitution and repression contribute to the occurrence of investigative errors during the acquisition, recording, and evaluation of testimonies.