Diploma thesis focuses on the procedural aspects of data mining from digital technology. Particularly it deals with the procedures for working with digital technology as a subject evidence in criminal proceeding. Author first deals with theoretical solution of evidentiary proceeding in terms of the current Code of Criminal Procedure. Then the author describes all the steps, which is necessary to do, that make data possible to use as an evidence in criminal proceedings. Finally, the author deals with the practical problems, with which legal experts meet, and he tries to propose solutions.