As the SS's leader, Heinrich Himmler used the SS to put the Final Solution into action. The SS Einsatzgruppen murdered many civilians, mostly Jews, in the countries controlled by Nazi Germany during World War II. The SS was in charge of creating and running concentration camps and death camps (camps where people were sent to be killed). In these camps, millions of prisoners died from many causes, including murder, starvation, disease, freezing to death, and being experimented on by Nazi doctors like Josef Mengele. 