Mintach served as the press secretary and representative for Congressman Joseph Boltzmann, a member of the German Parliament suspected of killing callgirl Erika Lemser after an alleged affair. Deeply convinced of his boss's innocence and trusting him implicitly, Mintach harshly criticized the BKA's investigation, particularly Inspector Lunge's handling of it. He became especially enraged and disturbed by Lunge's suggestions that he was trying to cover up his boss's affair. Pushed to the edge by Lunge's relentless and insensitive approach during the investigation, Mintach took his own life, still firmly believing in his boss's innocence, as stated in his suicide note.
Following Mintach's death, the BKA station chief and his team removed Lunge from the case due to the loss of a valuable reference and potential source of information. This left Lunge with only the Middle-Aged Couple Murders case, which he pursued with increasing fervor, narrowing his focus on Kenzo Tenma, the primary suspect in the murders (though they were actually committed by Johan Liebert and his associates).
(Source: Monster Wiki)
