  We present an \emph{ab-initio} approach for computing the photoionization
spectrum near autoionization resonances in multi-electron systems. While
traditional (Hermitian) theories typically require computing the continuum
states, which are difficult to obtain with high accuracy, our non-Hermitian
approach requires only discrete bound and metastable states, which are
accurately computed with advanced quantum chemistry tools. We derive a simple
formula for the absorption lineshape near Fano resonances, which relates the
asymmetry of the spectral peaks to the phase of the complex transition dipole
moment. Additionally, we present a formula for the ionization spectrum of
laser-driven targets and relate the `Autler-Townes' splitting of spectral lines
to the existence of exceptional points in the Hamiltonian. We apply our
formulas to compute the autoionization spectrum of helium, but our theory is
also applicable for non-trivial multi-electron atoms and molecules.
