Photoelectron ionization spectra of an autoionization system interacting with a neighboring two-level atom are studied using the method of canonical transformation. Conditions for the occurrence of a Fano zero are exactly derived, together with its frequency. Ionization spectra are typically composed of at most four peaks in this case. Sharp peaks occur not far from the Fano zero due to the confluence of bound-free coherences. Spectral peaks close to the Fano zero are suppressed. Also dynamical zeros appearing once per the Rabi period in conditioned photoelectron ionization spectra are observed.