The account, which is the same in every place it appears, is this. On December 2, 1920, homicide investigators in Spandau, on the western edge of Berlin, announced the arrest of a fifty-year-old cabman named Schultz on eleven counts of murder. The victims were said to include men, women and children, among them an eight-year-old killed in 1894 and, some years before that, his wife's two brothers. His wife was said to have kept silent for decades under threats to her own life and finally to have gone to the police, and the eleven counts rest on her account.
That paragraph is the entire source base. It descends from a single encyclopaedia entry built on the 1920 announcement. No first name for Schultz is recorded anywhere. No court report, sentence or execution record has been located, and the execution by guillotine in 1921 that this roster carries as his disposition rests on the same one paragraph.
The documented serial case in Spandau in exactly these years is a different man: Friedrich Schumann, the Falkenhagen Lake killer, tried in Berlin in 1920 and beheaded at Plotzensee prison on August 27, 1921. Nothing links the two accounts beyond place and date, and no conclusion should be drawn from the coincidence. Until a contemporary German source is found, this entry should be read as an unverified press announcement rather than as a case.