Analyzing a racketeer or white-collar criminal's personal expenditures can tip off the investigator, the prosecutor, and the jury that these individuals have been acquiring 'net worth' and have been making other personal expenditures at a rate far in excess of their income from legitimate sources, thereby creating an inference (admissible as circumstantial evidence) that they have income from illegitimate sources. The net worth investigative technique is simple enough for the criminal investigator untrained in accounting to use. Another comparatively simple investigative technique involves analyzing stock transactions; the author describes phases in this and the net worth analysis, with numerous illustrations. He also details admissibility rules for specific forms of documentary evidence and cites constitutional and statutory provisions relating to financial investigations. Interrogation techniques and report writing rules are mentioned.