Inspector Filip Zeman was Detective Jan Suk's superior. He was a high-level member of the Prague Police Department, but, secretly, he was also an unscrupulous former member of the Czechoslovakian Secret Police (StB), the remnants of which were largely involved and implicated in organized crime.
After questioning Wolfgang Grimmer regarding the murder of Reinhardt Biermann, the former head of Kinderheim 511 who Grimmer had recently been affiliated with, he allowed him to go but suspected that Grimmer knew the location of the key to a safety deposit box containing an audiotape recording of a young Johan Liebert from 511 Kinderheim that he and his colleagues were trying to sell on the black market. Therefore, he had two of his partners pick Grimmer up in a taxi, detain him, and drive him to a decrepit factory location, where he revealed himself as their co-conspirator and tortured Grimmer for information about the tape. When Grimmer refused to yield any information about it and lapsed into a state of semi-consciousness from the severity of his injuries (including several deep nail clippings inflicted by Zeman), the mysterious blonde woman who had accosted Biermann ("Anna Liebert", who was really Johan in disguise) arrived and shot one of Zeman's partners, before presumably invoking Grimmer's inherent rage in the form of his "Magnificent Steiner" personality, and inciting him to kill Zeman and his other partner, which he did as an act of utter physical brutality (evidenced by the aftermath seen and mentioned thereafter).
Jan Suk was sickened by the crime and seeing his mentor in such a state, but he eventually came to terms with the fact that Zeman, in spite of his kindness, was a corrupt, morally bankrupt man.