The total-ion-yield (TIY) spectrum of ozone has been recorded in the K-edge region for the first time with high photon energy resolution and without significant O-2 contamination. Spectral features have been clearly observed in the high energy region below the two ionization thresholds. The assignment for the core excitation processes from the "terminal" and "central" oxygen atoms, given for the first time in the whole spectral range, is based on high level ab initio calculations. The QDPTCI (quasidegenerate perturbation theory configuration interaction) theoretical approach provided an excitation energy pattern and photoabsorption oscillator strengths that were found in good agreement with the experimental TIY spectrum. The decay dynamics of the con excited resonant states is shown to be strongly dependent on the sigma/pi antibonding character of the virtual MO involved in the excitation process.