1. A forensic system configured to acquire digital information recorded in a plurality of computers or a server, to analyze the acquired digital information, the system comprising: a digital information acquiring unit configured to acquire digital information including digital document information having a plurality of document files and user information related to a user who uses the plurality of computers or the server; a recording unit configured to record the digital information acquired by the digital information acquiring unit; a display unit configured to display the recorded digital information and the user information; a designation accepting unit configured to accept designation of at least one document file included in the digital document information, and to accept designation of a specific language into which the at least one document file, the designation of which is accepted, is translated; a translation processing unit configured to translate the at least one document file, the designation of which is accepted, into the language the designation of which is accepted; a common document file extracting unit configured to extract a common document file representing the same content as that of the designated document file from the digital document information recorded in the recording unit; a translation-related information generating unit configured to generate translation-related information representing that the extracted common document file is translated by invoking a translated content of the translated document file, and information representing an output priority order of the plurality of document files; a control unit including: a multi-language full-text searching unit configured to perform a multi-language full-text search of the document files; and a managing unit including an access right control function configured to set one or more rights for each account of a browsing person; an incidental information setting unit configured to set incidental information representing whether document files of the extracted digital document information are related to a litigant; a language determining unit configured to generate a plurality of partial character strings from character strings of a predetermined language according to a predetermined rule, to evaluate a language to which each partial character string from among the plurality of partial character strings may belong, to search for a character string of the at least one document file stored in the recording unit, to discover the character string that is searched as being a match with one of the plurality of generated partial character strings, and to determine a language to which the discovered character string of the at least one document file belongs; and an output unit configured to output a litigant document file based on the translation-related information, the incidental information, and the output priority order of the plurality of document files.