Mitläufer

Mitläufer is a German term (plural: "Mitläufer") used in the denazification proceedings in West Germany after World War II to describe people who supported Nazism without directly participating in Nazi atrocities such as genocide. "Mitläufer" is usually translated in English as either "fellow-traveler" or "hanger-on". 
Other websites.
http://www.woxikon.com/wort/mitl%C3%A4ufer.php