Involved in the interrogation of Lucrețiu Pătrășcanu, he ensured Soviet intervention in the proceedings, and was personally responsible for the arrest of Lena Constante. He also played a leading role in the brainwashing experiment provoked by the Communist authorities in 1949–1952 at the Pitești Prison; he encouraged Eugen Țurcanu to carry out the task and carried out regular inspections, during which he would ignore evidence of torture. In the inquiry preceding the show trial for sabotage at the Danube-Black Sea Canal, Nicolschi led a squad of torturers that was entrusted with obtaining forced confessions from Gheorghe Crăciun and other employees.