We present the Localizer tool, which is targeted at assisting developers and testers in debugging their Python code. The tool combines program slicing and program spectra analysis to analyze the difference between the execution paths of the passing tests and of the failing tests, respectively. In addition, it suggests suspicious parts of the code where the fault can be potentially located. To assist the user in inspecting the code, the tool graphically presents the structure of the code as control flow graphs annotated with program spectra information. Preliminary studies show that the tool facilitates the identification of faults by reducing the complexity of the code analysis process.