The four victims were treated by the 39-year-old doctor who was arrested on Tuesday. He is now detained, suspected of manslaughter, arson and attempted arson.
The police believe that the doctor set fire to the women's residences to cover up his crimes. One of the women showed signs of life when the ambulance personnel arrived, but died later at the hospital.
The crimes were committed in the Neukölln and Plänterwald districts over six weeks in June and July.
The victims were between 72 and 94 years old.
