A method of locating a defect of a failed semiconductor device which includes applying a test pattern to the failed semiconductor device and providing failed semiconductor device test responses as a pass signature, applying radiation to each of multiple locations of circuitry of a correlation semiconductor device with sufficient energy to induce a fault in the circuitry, applying the test pattern to the correlation semiconductor device while the radiation is applied to the location and comparing correlation semiconductor device test responses with the pass signature for each location, and determining a defect location of the failed semiconductor device in which correlation semiconductor device test responses at least nearly match the pass signature. The radiation may be a laser beam. The method may include determining an exact match or a near match based on a high correlation result. Asynchronous scanning may be used to provide timing information.