Simplify the following text for a Grade 10 native English-speaking person.
Original: Wessel was assassinated by a Communist activist in January 1930 , and the propaganda apparatus of Berlin Gauleiter Dr Joseph Goebbels made him the leading martyr of the Nazi Movement .
Simplified: Wessel was murdered by an unknown assailant , possibly a Communist party member , in February 1930 , and Nazi propagandist Gauleiter Dr. Joseph Goebbels made him a martyr of the Nazi movement .