Beate Zschaepe, 41, worked in a store in the eastern German town of Zwickau that was run by the agent during Zschaepe’s time as an alleged member of the National Socialist Underground (NSU), which was formed in 1998.
The store’s operator was Ralf Marschner, who is believed to have worked under the code name Primus for Germany’s domestic intelligence service (BfV).
The NSU, which is thought to have committed a series of racially inspired murders, bank robberies and bombings, came to a dramatic end in November 2011 when two of its alleged members were found dead in the smoking ruins of a camper van in the eastern German city of Eisenach.
One of those who died in the apparent murder-suicide in the camper van after a botched bank robbery, Uwe Mundlos, also worked for Marschner, according to a report in the German daily Die Welt.
A spokeswoman for the BfV declined to comment on the reports.
Police investigating the murders of mainly Turkish immigrants allegedly committed by the NSU were initially convinced the deaths were the result of drug running, honour killings or family feuds rather than a neo-Nazi cell.
But a new fictionalized TV account of the NSU suggests that part of the reason the official police investigation into the group was mishandled was because the authorities were trying to protect their informants in the nation’s radical rightwing and neo-Nazi scene.
The third and final part of the TV series, German History X, screened on German state TV ARD on Wednesday.
In addition to being a member of a terrorist organization, Zschaepe is also charged with being an accomplice in the 10 murders that the group carried out between 2000 and 2007.
Zschaepe is the main defendant in the case, which has been running for about three years. Four others are also on trial for providing support to the NSU.
The trial is one of biggest in Germany since the 1970’s when members of the far-left Baader Meinhof Gang, also known as the Red Army Faction, faced a court.
A trained gardener, Zschaepe was arrested in 2011, a short time after she torched the apartment in Zwickau she shared with Mundlos and the other member of the NSU trio Uwe Boehnhardt, who was also found dead in the camper van in Eisenach.
Zschaepe has denied any knowledge of the execution-style murders, saying that Mundlos and Boenhardt had been responsible. She has also insisted that she had not been an NSU member.