Jan Richter, played by Christian Oliver, is the fourth colleague of Semir. Gerkhan, after the resignation of Tom Kranich, was in fact looking for a new colleague. After discarding yet another boy, Hartmut Freund, Semir must solve a case. Jan Richter stops him, but says he is an undercover cop. Semir distrusts him. After the clarification of the misunderstanding and the resolution of the case by both, Jan is about to return to his command, when Semir and Anna Engelhardt believe Jan is the right person to take Tom's place. Jan leaves the stage after a few seasons, suddenly and for no reason. In fact, the producers he disappeared from there soon to have Tom return, while Chistian had commitments on other sets. Semir and Jan have a strong bond that is formed very quickly, so because of this, Semir wanted him as a witness for Semir's wedding with Andrea Schaefer. Jan is very young and, in spite of this, is a cautious and good cop. He does not take action without first thinking carefully about what he is going to do. The fans have put forward many theories why he left: 1. Jan had taken for a girl he met on his last episode and then committed suicide, or 2. The great danger of dying during that same episode (Extreme) forced his leave.
Jan has driven the same Mercedes CLK's Tom has driven.