A thermal gradient is induced in a device-under-test (DUT) and used to determine the location of a defect. In one embodiment, a laser creates a moving thermal gradient from a test site on the DUT and a respective time of flight for the thermal gradient to trigger a condition associated with the defect is determined. Repeating the time of flight testing at additional test site provides information used to trilaterate the defect in three dimensions. Alternately, a static thermal gradient is induced across at least a portion of the DUT along a first axis. The thermal gradient is incrementally walked along the first axis until the condition associated with the defect is triggered, thereby defining a first region. The thermal gradient is then induced along a second axis of the DUT and the process is repeated to define a second region. The location of the defect is determined to be the intersection of the first region with the second region.