The book tells about people who were involved in the investigation of criminal cases in Russia in the first quarter of the 18th century. They worked in various investigative agencies - from the “major’s” offices to the Investigation Office of the Supreme Court. On the basis of archival documents, the vicissitudes of careers and the biographies of the first investigators, who were mainly officers of the Preobrazhensky and Semenovsky regiments, were covered almost for the first time. Along with this, unique details are given of the high-profile criminal cases they investigated, the bulk of which were initiated in cases of bribery and embezzlement of government officials at various levels. Previously unknown stories were examined, when investigators themselves were subject to criminal prosecution. From the book, the reader learns for the first time about many of the secrets of criminal justice during the era of the autocracy of Peter the Great.