In the first section, the author presents guidelines for the determination of undisclosed financial interests through the use of financial information retained by banks on a target's checks, deposits and expenditures, safe deposit box entries, and loan files. Additional information can be obtained from the analysis of brokerage accounts and such public records as real property records and the fictitious names index. Guidelines for tracing funds in foreign bank accounts also are presented. In the second section, additional financial investigation techniques are delineated. The net worth-expenditures principle is a mathematical computation designed to determine the total accumulation of wealth and annual expenditures of an individual. Application of this technique can be used to gather intelligence, enhance interrogation of a target, corroborate other evidence, determine havens where the target may be hiding assets, and identify assets for restitution or fine collection. The application of this principle in two formats, the net worth expenditure schedule and a schedule of source and application of funds, is illustrated in a practical exercise. A listing of additional sources of information and their use also is provided.