We present a fully quantum mechanical treatment of resonant scattering of gamma radiation in a nuclear medium exhibiting a Lambda scheme through level mixing. A framework is presented to derive the radiation intensity for N effective scatterers contributions. A closed-form solution for the radiation intensity is obtained and compared to the generic expression of EIT in an atomic Lambda scheme. Although the nuclear scheme does not fulfill EIT conditions, the observable effects are similar. We show that the change in polarization of the scattered radiation, due to the level mixing, gives rise to the development of a strong complementary polarization state which is delayed with respect to the incident photon to a reduction in absorption because this state does not interfere with the incident photon.