In Portland, Me., trash haulers have taken advantage of different tipping rates and billing for residential and commercial trash, as well as different rates for different communities. In the early 1990's, tonnage at the Regional Waste System (RWS) incinerator in Portland had been declining. The police investigative team examined RWS records for the previous five years month by month, broken down by hauler and community. It found that the decline was primarily in commercial rather than residential tonnage, a major clue that commercial trash (typically paid for by haulers through private contracts with customers) was being claimed as residential (paid for by local governments). Further analysis found that the residential tonnage received or claimed by haulers at RWS fluctuated inexplicably, at times far exceeding the "expected" tonnage from towns. Following the records check, the investigators observed trash collection and disposal, as the investigators targeted specific companies and municipalities. If a truck was observed picking up a load of commercial waste during the day, the investigators could determine whether that truck showed up at RWS and whether the load was identified as commercial. The third phase of the investigations was an examination of hauler records. The process of analyzing these records and comparing them to both the RWS analysis and the surveillance results took almost a year. The final phase of the investigation focused on customer lists and route sheets from companies. The investigation found that the most frequent crime was to lie about the origin of the trash. This is "theft by deception" in the Maine criminal statutes. Recommendations are offered for ways to prevent this offense by trash haulers and to institute effective investigative procedures.