The presence of crystalline defects, including dislocations and pipeline defect, is detrimental to both the processing and the intrinsic quality of semiconductor devices. The electrical parametric or functional failures generated by those defects require accurate identification and proper classification in a continuous improvement mindset. Depending on the failure analyst choice of the investigation technique, the distinction between a dislocation and a pipeline defect can be difficult. In this paper, based on case studies of mixed-mode devices, the various electrical and physical FA investigation techniques are explored and compared. From an electrical investigation standpoint, fault localization techniques will be reviewed (Thermal Laser Stimulation and Photon Emission Microscopy) as well as the direct electrical measurements means (external measurement and nanoprobing AFP). From a physical analysis standpoint, the use of various methods after deprocessing will be considered: top down delineation etch, Atomic Force Microscopy (AFM), Scanning Microwave Microscopy (SMM), and Transmission Electron Microscopy (TEM). The position of the defect as well as its physical signature observed through the various methods will determine its proper classification and will determine the appropriate corrective actions. The paper will be concluded with a discussion on the physical differences between a dislocation and a pipeline defect, as well as insights into the wafer fab manufacturing process.