Although methods exist for the processing of oil or grease prints on items of evidence, it has proven problematic and most often ill-fated to develop fingerprints on items of evidence that have been completely coated with petroleum-based products. Attempts to safely remove the contaminant, while preserving and developing the underlying fingerprints, have had little or no success. Experimentation demonstrated that heptane can effectively remove a petroleum product, such as gasoline, from nonporous surfaces, thus preparing the surface for subsequent successful latent print processing with currently accepted methods for the development of oil and grease prints. (Published Abstract)