Das Geheimnis des Totenwaldes S01E05 - Das verbotene Zimmer

Together with a private team of investigators, the so-called core team, Bethge reopens his sister's case after his retirement, obtains all the files and manages to get into Becker's "secret" room again. There, even many years later, there were overlooked indications of a serious suspicion. Did his sister fall victim to a mysterious serial killer?