This article presents original and previously unpublished documents from the case of Van’ka Kain (1741–1748). Van’ka Kain was a notorious Moscow criminal who surrendered at the end of 1741, declaring his wish to help the police round up his former associates in crime. More than one hundred criminals (professional thieves, criminal hideouts’ keepers and fencers for stolen goods) were arrested by Kain and the soldiers in a few days’ time. Kain was rehabilitated in the spring of 1742, becoming an official informer and detective of the Sysknoi prikaz (Office of Criminal Investigation). In such capacity he assisted in the apprehension of his past confederates, professional thieves, until 1748. The materials of his case published in this article for the first time contain unique and comprehensive information on the Moscow underworld of the 18th century.
The paper characterizes the first steps in research eminent specialist in archeography, source studies, research Metrica of the Grand Duchy of Lithuania.