<p>While the static theory for understanding defect properties in semiconductors in equilibrium has been established for decades, it fails to identify the crucial defects in nonequilibrium, such as under irradiation. In this paper, we develop a robust ab initio-driving multiscale modeling framework to identify deep-level defects in irradiated semiconductors with multidimensional defect properties. It overcomes two challenges unsolved in the past studies, that is, unambiguous nonequilibrium defect identification and exact deep-level transient spectroscopy (DLTS) simulation. Our method, verified by identifying the well-known deep-level defects in neutron-irradiated Si, is successfully applied to identify the controversial deep levels in neutron-irradiated wide-bandgap semiconductor, 4H-SiC, contributing to solving the half-century mystery of their atomic origin. Furthermore, we discover that defect origins of the same DLTS peaks vary significantly with annealing temperature, due to different defect types with distinct dynamic behaviors, breaking the long-lasting belief derived from the static defect theory. Our study not only expands the understanding of nonequilibrium defect physics of semiconductors, but also lays a solid foundation for controlling targeted crucial defects to improve material properties and device performances.</p>