on 3 december 1941, he was promoted as commander of ek2, replacing eduard strauch. lange was also the area chief of the "sicherheitsdienst" (sd), the nazi security service, with the title "kommandant des sicherheitsdienst". he was in charge of department iv of the sd in latvia. the department was the "hub of the whole sd organization in latvia, the other departments served it." matters of formal rank and titles were never clear in the nazi occupation regime for latvia, as the lines of authority within agencies and the relationship between one agency and others were "ambiguous, overlapping, and unclear". nevertheless, lange is widely recognized as one of the primary perpetrators of the holocaust in latvia.