In a high J-value scheme (photo-excitation sequence), the authors investigate the characteristics of three-step photo-ionization, through an autoionizing level, of a complex atom using three single-mode pulsed dye lasers. The report covers (1) ion yield dependence on the balance of three laser intensities; (2) AC Stark effect, observed in intermediate excitation; and (3) multi-photon-resonance effect in a stepwise near-resonant excitation. The experimental results are discussed through comparison with the theoretical analyses, that include the effects of magnetic sublevel degeneracy.