This project responded to allegations that a home heating oil dealer was cheating customers by producing false delivery slips showing amounts that exceeded by 30 percent or more the gallons actually delivered. The police seized meters attached to each of the three delivery trucks and a metal box containing a printing unit found during a search of the owner's premises. Invoices billed to two large apartment blocks during fall 1979 and winter 1980 were analyzed. The components and characters that formed the box's printing unit were similar to the devices in the three meters. The meters bore Federal Government seals which had to be broken to remove the head cover. Differences in width and design of characters and resulting impressions, along with some individual features, allowed an initial separation of the questioned invoices into four groups. One company meter was quickly eliminated on the basis of differences in class characteristics. The laboratory found that only 15 percent of the questioned impressions were printed by the official meters. The homemade printing unit found in the box produced about 10 percent of the questioned imprints, and the remaining 75 percent displayed features indicating they had been produced by another printing unit not submitted to the laboratory. Photographs and one reference are included.