Investigation diary requirement: mandatory, paginated police record used to aid trials but not as evidence. Section 192 requires investigating police officers to maintain a daily, duly paginated diary recording times information was received, investigation start and end times, places visited, circumstances ascertained, and to insert witness statements recorded under section 180. Criminal Courts may call for and use such diaries to aid inquiry or trial but not as evidence; the accused and agents have no automatic right to obtain or inspect them. If the diary is used to refresh an officer's memory or to contradict the officer, the procedures in section 148 or section 164 of the Bharatiya Sakshya Adhiniyam, 2023 apply.