  We derive exact analytical expressions for the spectral density of the Dirac
operator at fixed \theta-angle in the microscopic domain of one-flavor QCD.
These results are obtained by performing the sum over topological sectors using
novel identities involving sums of products of Bessel functions. Because the
fermion determinant is not positive definite for negative quark mass, the usual
Banks-Casher relation is not valid and has to be replaced by a different
mechanism first observed for QCD at nonzero chemical potential. Using the exact
results for the spectral density we explain how this mechanism results in a
chiral condensate that remains constant when the quark mass changes sign.
