CdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS, and additional cladding layers of CdS. The luminescence spectrum of the studied materials contains a dominant exciton band located at the HgS layer and an additional nonexcitonic band, presumably corresponding to the recombination of trapped carriers. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated species. These properties were investigated by the utilization of optically detected magnetic resonance spectroscopy. The results have shown the existence of two kinds of electron-hole recombination, trapped either at a twin packing of a CdS/HgS interface or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.