We report on the state-selective detection of near-dissociation ultracold KRb molecules in the ground $X\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}^{+}$ state and the metastable $a\phantom{\rule{0.2em}{0ex}}^{3}\ensuremath{\Sigma}^{+}$ state. The molecules are produced by photoassociation of ultracold atoms followed by radiative decay into high vibrational levels of the
X and
a states. Detection utilizes resonance-enhanced one-color two-photon ionization, followed by time-of-flight mass spectroscopy. Scanning the detection laser frequency over the range
582−−625nm, we observe transitions from the ${v}^{\ensuremath{''}}=86--92$ levels of the
X state, which are bound by up to $30\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, and the ${v}^{\ensuremath{''}}=17--23$ levels of the
a state, which are also bound by up to $30\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. The measured vibrational spacings are in excellent agreement with those previously measured and those calculated from the relevant potential curves. Relative vibrational populations are also consistent with Franck-Condon factors for decay from the photoassociated levels.