Answer
The SA, or Sturmabteilung, killed Horst Wessel's murderer after the Nazis gained power in Germany. Wessel was a prominent Nazi SA member who was shot and killed by a communist in 1930. The Nazis used Wessel's death as propaganda to garner support for their cause. After Hitler became Chancellor in 1933, the SA took revenge by killing Wessel's murderer, thus avenging his death.