We report a deperturbation analysis of the [18.5]1-X0(+) system of ReN. Heterogeneous J(a) uncoupling involving a ''dark'' (Omega = 2) state is responsible for the observed perturbation. For the (0-0) band located near 540 nm, extra branches as well as an irregular energy level pattern are observed. For the (1-0) band near 510 nm, although the observed spectrum appears regular, the B' value deduced from a previous analysis is not consistent with values associated with other vibrational levels. A careful reexamination of this band, using dispersed fluorescence to filter the laser induced fluorescence (LIF) spectra, allowed us to separate the ''bright'' and ''dark'' state contributions to the original LIF spectrum. In fact two spectra can be obtained, corresponding mainly either to the ''bright'' or to the ''dark'' excited states. Rotational analyses have been carried out for both of these (1-0) bands and confirm the deperturbation analysis of the (0-0) bands. Excited state lifetimes have been measured for individual re-vibrational levels of the ''bright'' state. These lifetimes exhibit a large variation with rotational and vibrational quanta, an effect consistent with the proposed heterogeneous uncoupling mechanism. Dispersed fluorescence spectra have been recorded for all previously observed excited states. These spectra reveal the presence of a number of new low-lying states and the analysis helps to establish their Omega values. The current observations are consistent with the previously proposed electronic structure. However, the Franck-Condon factors inferred from the present study;suggest that strong interactions exist among many of the excited states.