The counterfeiting of semiconductor devices has become an important contributor as more components are used in the increasingly sophisticated audio and navigation systems while more suppliers are moving manufacturing plants off-shore. This paper presents a case study on how the authors were able to identify a counterfeit device and certify a replacement source. In this study, failed devices with Intersil CA3080 Operational Transductance Amplifier IC from factory testing and field returns in suspect lot codes were purchased from a second source, due to the unavailability of the obsolete device from the regular first source. The suspect lot codes that were not recognizable by the manufacturer were determined to be counterfeit devices. Many pieces of physical evidence suggested that the failed devices were not consistent with genuine devices directly purchased from the manufacturer.