TV-Series
Description
Dr. Rudy Gillen is a forensic psychologist and criminologist in Germany who studied medicine alongside Dr. Kenzo Tenma. He is a well-respected figure in his field, known across Europe for his numerous books on criminal psychology, and his success eventually places him on Germany's list of fifty highest taxpayers. Gillen possesses a highly analytical mind, sharp intuition, and a deep understanding of the criminal psyche, which he applies to his research and consultations for law enforcement.

His personality is defined by a fierce drive to be the best. He hates receiving anything less than top marks and can become quickly irritated if he feels he is being looked down upon or condescended to. This competitive nature stems from his university days, where he developed a one-sided rivalry with the more popular and high-achieving Tenma, harboring feelings of jealousy and inferiority. A defining incident from this period occurred during a difficult exam on medical law. Feeling desperate, Gillen cheated by using a hidden cheat sheet. Kenzo Tenma noticed the act but never reported him. Despite regaining his top ranking, Gillen spent years in paranoia, believing Tenma possessed a secret that could ruin him.

Professionally, Gillen has a distinctive habit of recording all his conversations and feels uncomfortable speaking without his cassette recorder, a method that is central to his analytical process. This devotion to his work came at a personal cost; his wife left him three years before the story begins, accusing him of being a collector who only peeks into the hearts of others and who paid more attention to his recording device than to her.

Within the narrative, Dr. Gillen plays a crucial role as an investigator. He becomes involved in the search for Johan Liebert through his connection with Dr. Julius Reichwein, his former professor. His initial encounter with Tenma is adversarial; he believes Tenma may be a serial killer with dissociative identity disorder and even collaborates with the police to set a trap for him. This belief changes after his research with a serial killer named Peter Jurgens. Through an interview, Gillen discovers that one of Jurgens' murders did not fit his established pattern and was committed at the request of a friend named "Johan." This corroborates Tenma's story and leads Gillen to conclude that Johan is a real, manipulative figure who can control other murderers.

Convinced of Tenma's innocence, Gillen aids his escape from the police during a tense meeting. He reveals his own past cheating to Tenma, confessing his long-held guilt, and produces a fake cheat sheet that actually contains escape instructions. Acknowledging the resolution of their old rivalry, Tenma confesses that he also cheated on that same exam, fully absolving Gillen. Following this, Gillen forms a close partnership with Dr. Reichwein to gather concrete evidence of Johan's existence and help clear Tenma's name. His expertise is further utilized when he places Nina Fortner under hypnosis to recover her repressed and traumatic childhood memories of Johan, a process that yields crucial information about their past.

Dr. Rudy Gillen is an example of intellectual integrity and professional dedication. He overcomes a deep-seated personal flaw by setting aside his jealousy to pursue the truth, proving instrumental in providing the protagonists with psychological insights and evidence to understand and stop Johan. In the end, he channels his experiences into his work, writing a book about the case that becomes a popular success.
Cast