On the radar before murders?

Investigators in the eastern state of Saxony in a letter dated April 28, 2000 - before the NSU allegedly committed its first of 10 murders in Germany - wrote that the trio now known as the National Socialist Underground could be considered similar to a terror cell.

"The group's methods resemble the strategy of terrorist groups, which pursue a collective goal through the division of tasks," the letter said, adding that in the trio's particular case, "a considerable increase in intensity up to and including the most serious crimes is identifiable."

Public broadcaster SWR aired its "Report Mainz" investigative journalism feature on national sister broadcaster ARD on Tuesday night. Regional ARD offshoots like SWR often save their prime material for first release on the national channel.

The document is printed bearing the letterhead of the then president of the Saxony state's domestic intelligence agency. Klaus Hardraht, regional interior minister at the time, is among the addressees.

At this point, Uwe Böhnhardt, Uwe Mundlos and Beate Zschäpe were under surveillance for other crimes, and the letter was justifying upping their surveillance to the highest available "G10" level, which includes tapping phones and intercepting letters. This monitoring system was approved and implemented from May to October of 2000, but with little success.

Gone, and then forgotten?

Authorities were particularly concerned by their ability to go to ground so professionally, leaving barely a trace, once they became aware of police attention. Such an effective disappearance "would not have been achievable" without help, the letter said: "Such an escape is possible only with the closest of connections within a closed loop of a few, discrete confidants."

Accused of 10 killings, among other crimes, the NSU is alleged to have committed its first murder in Nuremberg in September 2000.

A former government spokesman, Uwe-Karsten Heye, told Report Mainz that the letter ultimately showed that if the German authorities "had stayed on the case, this series of murders might never have happened."

Zschäpe is the only surviving alleged core member of the NSU and is currently facing trial in Munich for her role in the group's activities, along with four alleged accomplices. Mundlos and Böhnhardt were found dead by police in November 2011; they had taken their own lives after a botched bank robbery. Police also found the service weapon of a dead policewoman, believed to be one of the NSU's victims, at the scene - a key early piece of evidence in unraveling the case.

German authorities were already on the back foot over the NSU. As well as some investigative irregularities including the destruction of potentially pertinent paperwork after the NSU was uncovered, investigators first suggested that the killings now believed to be the work of a German far-right group were instead organized crime among immigrant communities. The federal head of the domestic intelligence agency resigned in the aftermath, along with some of his regional colleagues. A parliamentary committee was established to investigate and described the authorities' failure as "peerless" in a report in the Bundestag last week.

Saxony's intelligence agency is moving out of its old offices in Dresden; SWR concluded its program by saying this letter was found by chance in the process, and had "evidently not been touched" in a decade.

msh/dr (AFP, dpa)