Long ago, he was Isaak Sirko's music teacher.
While Isaak is sitting with Nadia in George Novikov's office, he brings up his music teacher. He tells her that Mr. Chillich had said, “Isaak, you think you’re strong, but you are not strong if you don’t feel.” His teacher then gave him an "F" in class, so Isaak pushed him down a flight of stairs. He claims that he felt bad about it. After this incident, Isaak's father sent him off to a disciplinary school in England. Isaak tells Nadia that the only thing remaining of his sensitive side is his love of Opera.
It is not stated whether Mr. Chillich died from the fall. If so, he could be Isaak's first personal kill resulting from anger.