Inspector W. Clausen is the stern head of the federal task force investigating the disappearances in Winden, as well as the mystery relating to his late brother, Aleksander Köhler. "Clausen" is his family name; his given name is unknown, although the initial "W." is seen. He was last seen in season 2 .
The Winden Police have been unable to determine the fates of four missing children—Erik Obendorf, Mikkel Nielsen, Yasin Friese, and Jonas Kahnwald—or their own officer, Ulrich Nielsen, and also Helge Doppler. Nevertheless, the townsfolk's reception to Clausen is frosty. Jürgen Obendorf is furious that the "task force" consists only of Clausen and Charlotte Doppler, who had led the failed local investigation. The others are wary of Clausen uncovering their own misdeeds, lying to him or giving him evasive answers. The contempt soon becomes mutual, from his conversation with Torben Wöller:
- "We have a man-eating cave, a nuclear power plant with a boss who is obviously hiding something, a detective who has gone into hiding, and a town full of people who lie, cheat and betray one another, and who are all only concerned with concealing what's really going on here."
Nevertheless, Clausen is a methodical and meticulous investigator. He believes a single investigator who sees the big picture will have superior insight to multiple investigators who only work on a small portion of the case, and so insists upon interviewing everyone again himself. As he has no driver's license, he has Charlotte, then Torben, chauffeur him around Winden.
His suspicions center on the connection between the power plant, the Winden Caves, and Aleksander Tiedemann; he takes a peculiar interest in Aleksander taking his wife's name after their marriage. It emerges that the missing children are not the main focus of Clausen's interest. He is trying to find the murderer of his brother, Aleksander Köhler, in Marburg in 1986—just prior to Aleksander's arrival in town. An anonymous letter sent a few months ago had tipped him off that he would find answers to his brother's case in Winden.
Clausen finds Aleksander's eagerness to change his name suspicious, as are his payments to Hannah despite the discontinuation of his massage therapy sessions. He has information from the civil registry in Marburg that there was only one Aleksander Köhler in Marburg—and it was not to the man calling himself Aleksander Tiedemann, who is a few centimeters too tall. He has Aleksander arrested on the charge of identity theft, further vowing that if he cannot prove that Aleksander is the murderer, he will at least uncover whatever secrets he is hiding at the power plant.
Clausen has Aleksander arrested, and leads the search of the power plant himself. He insists upon inspecting the old spent fuel chamber, himself donning a radiation suit, and then orders that the concrete sealing the old pool be torn up, revealing the yellow barrels of nuclear waste that had been hidden there. Ignoring Charlotte's plea to stop, he orders that the drum be opened up, contributing to the apocalypse that followed. He dies in the event.
- "Expectations lead to disappointment. Have hope, not expectations. You might just be surprised, but not disappointed."
- "I've been here almost a week, and I get the impression no one is telling the truth. Everyone's trying to hide something—although I'm not sure if you're all hiding the same thing, or if everyone is trying to keep their own skeleton in the closet."
- "Nothing beats a good neighborhood. It's remarkable that Mrs. Nielsen feels the same way about that. Oh well, maybe that's how small towns are. People share not only secrets, but also their money and beds."
Clausen complains about the dishonesty and self-serving he sees in the residents of the town. At the same time, however, he requested to be placed on the investigation not because of his interest in Winden's missing persons, but to further his own agenda of tracking down his brother's murderer. He keeps this motive a secret until he finds his suspect.
- Dark Season 2 Episode 1: "Beginnings and Endings"
- Dark Season 2 Episode 4: "The Travelers"
- Dark Season 2 Episode 2: "Dark Matter"
- Dark Season 2 Episode 7: "The White Devil"
- Dark Season 2 Episode 8: "Endings and Beginnings"
- Dark Season 2 Episode 1 "Beginnings and Endings"
- Dark Season 2 Episode 5: "Lost and Found"
- Dark Season 2 Episode 5: "Lost and Found"