 Hanecki first met Lenin in Brussels in 1903, and was in contact with him in Finland in 1907, and assisted him in moving his household to Cracow in 1912.He also persuaded Lenin to intervene in Polish affairs, siding with the Rozlamovists against Leo Jogiches and Rosa Luxemburg, and became one of Lenin's most trusted agents.He acted as chairman of the three man committee - whose other members were Lenin and Grigori Zinoviev - who looked into whether Roman Malinovsky, the former head of the Bolshevik parliamentary delegation, was a police spy, and wrongly exonerated him.