What is so special about this group is that they operated in modern times and got away with it for over a decade.
The NSU or National Socialist Underground appears to have been made up of 3 members; 2 men and one woman. They funded their ops by bank robbery, a common WN protocol.
One weakness of the NSU’s method was that they used the same gun in most of the killings. Remember, each gun produces distinct twist and lands/grooves patterns. That’s how the police surmissed that one gun was used in all the homicides.
Below is a video series, in German, on the group. They started small and climbed the ladder.