Recently a significant modification in the composition of a preparation named LiDa has been observed. GC-MS analysis of capsules content performed at the Forensic Examination Bureau, Internal Security Agency indicates the presence of an individual component similar to sibutramine. After isolating the component by column chromatography and performing a series of examinations using infrared spectroscopy (IR) as well as proton (¹HNMR) and carbon (¹³C NMR) magnetic resonance, the unknown component was identified as N-desmethylsibutramine hydrochloride. The correctness of the structure determination was confirmed by synthesis of the reference material.